Packet transferring/transmitting method and mobile communication system

ABSTRACT

A packet transferring/transmitting method is provided for use in a mobile communication system  50 . In this packet transferring/transmitting method, an upper node  1  determines the implementation of handover (determination step), and a handover addressing node  2  transfers, of a plurality of packets, a non-transmitted residual packet to a handover addressed node  3 , and the upper node  1  transmits a new packet to the handover addressed node  3  (transfer/transmission step). This enables maintaining the number of users to be accommodated while securing a wide bandwidth, sharing a line with high efficiency at soft handover, avoiding data residual in the case of the employment of variable communication rate, and preventing an increase in retransmission.

TECHNICAL FIELD

The present invention relates to soft handover at high-speedlarge-capacity communications in a W-CDMA (Wideband-Code DivisionMultiple Access : Wideband CDMA) system, and more particularly to apacket transferring/transmitting method and mobile communication systemsuitable for DSCH (Downlink Shared Channel) and HS-DSCH (High SpeedDownlink Shared Channel).

BACKGROUND ART

In recent years, the development of a CDMA mobile communication systemhas been in a prompt advance. Moreover, a commercial service based onthe W-CDMA system has started, which enables the transmission/receptionof large-capacity data such as moving images along with voices and stillimages included in the current main services. In this situation, as agroup for the standardization of a third-generation mobile communicationsystem, 3GPP/3GPP2 (3rd Generation Partnership Project/3rd GenerationPartnership Project 2) has been organized, which is oriented to a systemcapable of realizing a higher-quality service and prepares diversespecifications according to a W-CDMA mode and others.

FIG. 38 is a schematic illustration of a configuration of a W-CDMA. TheW-CDMA system shown in FIG. 38 is made up of nodes including a corenetwork (CN) 100 including an exchange 101, radio network controllers(RNC) 102-0, 102-1, base stations (BTS: Base Transmitting Station) 103-0to 103-5, and a mobile unit (UE: User Equipment). In this case, unlessotherwise specified particularly, the node signifies a unit made tocarry out functions of switching, transmission and transfer of a packet.Moreover, the nodes 101, 102-0, 102-1, 103-0 to 103-5 and 104 arephysically connected through an ATM (Asynchronous Transfer Mode)transmission line.

The handover prescribed in 3GPP is for switching a radio resource (radiochannel, radio carrier) such as transport channel while maintainingnon-instantaneous chopping and quality in a case in which the mobileunit 104 separates from the base station 103-1 which has been incommunication relation thereto before the handover and shits to acommunication area of a different base station 103-2, and this switchingis realized by soft handover.

FIG. 39(a) is an illustration of a state before the handover, and themobile unit 104 shown in FIG. 39 (a) sets one branch (physical radioline or radio link) with respect to each of the base stations 103-1,103-2 of the base stations 103-0 to 103-5 for transmission/reception ofa radio frame. Moreover, the mobile unit 104 transmits the same datasimultaneously to the respective base stations 103-1 and 103-2. The basestations 103-1 and 103-2 transmit the received data through an ATMtransmission line to the RNC 102-0. The RNC 102-0 processes these dataand transmits them through the ATM transmission line to the exchange 101side or the other base station 103-0 to 103-5.

In addition, for the handover, the mobile unit 104 monitors the qualityand others of the received data to monitor the radio situation (radiowave state) at all times for selecting and demodulating the data with ahigh quality. Thus, the mobile unit 104, when receiving a radio frame(radio signal) with a large electric field strength in conjunction withits movement, adds a new branch with respect to the base station 103-0to 103-5 transmitting this radio frame.

FIG. 39(b) is an illustration of a state after the handover, and whenthe quality of the branch of the set base station 103-2 degrades withthe movement of the mobile unit 104, the mobile unit 104 releases anddeletes this branch and makes a communication with the base station103-1.

Through this soft handover procedure in the mobile unit 104, the radiolink is continuously switched without instantaneous chopping.

However, the number of channels needed for when the mobile unit 104conducts the soft handover is at least two channels for the handoveraddressing node and the handover addressed node. The band needed for thetransmission/reception of a radio frame becomes twice the normal band.In addition, since the band needed per channel increases with anincrease in the communication data transmission rate (communicationrate), in a case in which the mobile unit 104 transmits the same signalthrough a plurality of channels in a handover state, the bandwidth to beused per user extremely increases. This increased bandwidth enhances theinterference in a radio zone, thereby causing the degradation of thecommunication quality and decreasing the number of users to beaccommodated.

For solving the increase of the bandwidth and the decrease of the numberof users through the use of a conventional technique, there is a need toimprove the throughput required in each node and each transmission lineand to increase the number of facilities, which leads to a considerabledemerit in view of cost performance. Moreover, there are the followingproblems (S1) to (S5).

(S1) Since, in a high-speed data communication in the future, thebandwidth needed for signal transmission/reception will becomesextremely large and the introduction of the metered charge will advance,as the connection method, a method of setting a line at all timesirrespective of the presence or absence of data will become a mainstreamapproach. From the viewpoint of efficiency, in the W-CDMA system, as apreferable method, only one shared channel (shared line) having asufficiently wide band as compared with a method of a wide-band radioresource being allocated to each mobile unit 104 is prepared so that therespective mobile units 104 share and use the channel when needed. Onthe other hand, difficulty is experienced in simultaneously transmittingthe same data to a plurality of channels at all times like the softhandover.

(S2) In this case, the mobile unit 104 is required to make the switchingfrom the shared channel for the handover addressing node to the sharedchannel for the handover addressed node, and the instantaneous choppingoccur in data communication while the mobile unit 104 makes theswitching. Moreover, in consideration of the introduction of IP(Internet Protocol) for an transmission line and the speed-up of datacommunication, in comparison with a method of a large volume of databeing divided into a large number of small packets and transmitted, itis preferable to employ a method in which data is transmitted to a lowernode in the form of one packet and the lower node divides this data inaccordance with the communication rate in a radio zone so that thedivided data are transmitted to the mobile unit 104. This provides ahigher transmission line service efficiency.

Therefore, in light of this efficiency and the above-mentionedinstantaneous chopping, there is a possibility that, in a handoverstate, the data collectively received and held by a handover addressingnode is left without being all transmitted.

(S3) For preventing data loss, a conventional method is designed suchthat an upper layer of a handover addressing node abandons the residualdata of the handover addressing node itself and retransmits it accordingto a host communication protocol. However, an increase of thisretransmission causes the degradation of the communication rate.

(S4) Likewise, the increase of the retransmission leads to an increasein unnecessary traffic, which presses the throughput (for example, thecapability of protocol processing, signal transmission/reception, chargeprocessing and others) of each node and each transmission line. That is,the cost performance of the facility deteriorates.

(S5) the real-time performance on communications degrades, which leadsto the degradation of quality of service.

The present invention has been developed in consideration of theseproblems, and it is an object of the invention to provide a packettransferring/transmitting method and mobile communication system capableof maintaining the number of users to be accommodated while securing awide bandwidth, sharing a line efficiently at soft handover, avoidingdata residual at the employment of variable communication rate andpreventing an increase in retransmission.

DISCLOSURE OF THE INVENTION

Thus, according to the present invention, a packettransferring/transmitting method for use in a mobile communicationsystem including an upper node for transmitting a plurality of packetsaddressed to a mobile unit, a handover addressing node for transmittinga plurality of packets addressed to the mobile unit and a handoveraddressed node for transmitting a plurality of packets addressed to themobile unit, characterized by comprising a determination step in whichthe upper node determines the implementation of handover and atransfer/transmission step in which the handover addressing nodetransfers, of the plurality of packets, a non-transmitted residualpacket to the handover addressed node and the upper node transmits apacket to the handover addressed node.

This eliminates the need for the handover addressed node to transmit thesame signal through the use of a plurality of channels to the mobileunit at handover, which enables an increase in number of users and animprovement of communication quality and achieves the effectiveutilization of transmission lines and radio resources.

This transfer/transmission step can employ the following two patterns ofa pattern A and a pattern B.

-   -   (A) A method in which the handover addressing node or the upper        node itself suspends the transmission of a packet from an upper        node at transfer of the aforesaid residual packet. This method        can achieve the improvement of the service efficiency of the        radio resources. Moreover, a new packet and transfer data can be        transmitted concurrently.    -   (B) A method including a channel setting step in which the upper        node carries out one of allocation of a separate transfer        channel and securement of an added channel between the handover        addressed node and the handover addressing node on the basis of        a packet volume in a radio zone, a scheduling step in which the        handover addressed node carries out scheduling on packet        transmission through the use of the separate transfer channel or        added channel secured in the channel setting step and a new        channel, and a scheduling transmission step in which the        handover addressed node transmits a packet and a residual packet        to the mobile unit on the basis of the scheduling in the        scheduling step. This method can prevent the missing of packet        transmission/reception through retransmission control to assure        the integrity.

In addition, in the aforesaid each transfer/transmission step, it isalso appropriate that the handover addressing node first-encapsulates aresidual packet according to an instruction from the upper node or theidentification of a received frame, and the handover addressed nodesecond-encapsulates the residual packet and transmits the residualpacket to the mobile unit. This can assure the integrity on each of thedata communication between the handover addressing node and the handoveraddressed node and the handover addressing node and the mobile unit.

Still additionally, in the aforesaid each transfer/transmission step, itis also appropriate that the handover addressed node conductstransmission/reception of a frame with respect to the mobile unit on thebasis of an association table between a header given by the handoveraddressing node and a header given by the handover addressed node. Inthis case, the handover addressed node can insert discriminationinformation for a discrimination between an encapsulated packet and anormal packet into a frame to be transmitted to the mobile unit. Thiscan assure the integrity of the data communication and enableshigh-speed processing.

Furthermore, a mobile communication system according to the presentinvention is characterized in that a handover addressing node comprisesa first line receiving unit for receiving a packet from an upper node, abuffer for holding the packet received in the first line receiving unit,a first retransmission control unit for carrying out retransmissioncontrol on a packet volume to be transferred on the basis of a resourcecapacity of a handover addressed node included in the packet received inthe first line receiving unit and a residual volume of the packet heldin the buffer, and a first line transmitting unit for, on the basis ofthe packet volume retransmission-controlled in said first retransmissioncontrol unit, transmitting the packet held in the buffer to the handoveraddressed node without interposing the upper node therebetween or by wayof the upper node.

This can prevent the loss of user data and improve the quality ofvarious types of services such as the stability of communication rateand the real-time performance.

Still furthermore, a mobile communication system according to thepresent invention, including an upper node for transmitting a pluralityof packets addressed to a mobile unit, a handover addressing node fortransmitting a plurality of packets addressed to the mobile unit and ahandover addressed node for conducting transmission/reception of apacket with respect to the mobile unit after the handover, ischaracterized in that said handover addressed node comprises a secondline receiving unit for receiving a plurality of packets from the uppernode and the handover addressing node, a second retransmission controlunit for carrying out retransmission control on a packet received in thesecond line receiving unit, and a second transmitting unit for giving aretransmission control header undergoing retransmission control in thesecond retransmission control unit to a plurality of packets received inthe second line receiving unit to transmit a radio frame with the headerto the mobile unit.

This enables a change of a frame format to be radio-transmitted throughthe use of an instruction from the upper node and enables a constantbuffer capacity of the handover addressed node.

Yet furthermore, a mobile communication system according to the presentinvention, having a function to switch a transmission path, from anupper apparatus to a mobile unit, from transmission by a handoveraddressing node to transmission by a handover addressed node, ischaracterized in that the handover addressing node comprisestransferring means for transferring data, addressed to the mobile unitand left in the handover addressing node, to the handover addressed nodeat the switching and the handover addressed node comprises transmittingmeans for transmitting, to the mobile unit, the data transferred andreceived therefrom and the aforesaid data from the upper apparatus.

This can improve the real-time performance of communications and thequality of services. The number of times of retransmission is reducible.

This mobile communication system can also suspend the transmission ofdata from the aforesaid upper apparatus to the aforesaid handoveraddressed node in the middle of the transfer by the transferring means,which can contribute to the optimization of radio resources and canimprove the cost performance in the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a configuration of an essential part of aW-CDMA to which the present invention is applied.

FIG. 2 is a block diagram schematically showing an upper node accordingto a first embodiment of the present invention.

FIG. 3 is a block diagram showing a base station according to the firstembodiment of the present invention.

FIG. 4 is a block diagram showing a base station according to the firstembodiment of the present invention.

FIG. 5 is a block diagram showing a mobile unit according to the firstembodiment of the present invention.

FIG. 6 is an illustration for explaining a packettransferring/transmitting method according to the first embodiment ofthe present invention.

FIGS. 7(a) to 7(e) are illustrations for explaining an operation of apattern A according to the first embodiment of the present invention.

FIG. 8 shows an example of a sequence for explaining an operation of thepattern A according to the first embodiment of the present invention.

FIGS. 9(a) to 9(c) are illustrations for explaining a pattern Baccording to the first embodiment of the present invention.

FIG. 10 is an illustration for explaining an arbitration method based ona resource allocation request according to the first embodiment of thepresent invention.

FIG. 11 is a flow chart for explaining a transferring method based onmeasurement of a free buffer capacity according to the first embodimentof the present invention.

FIG. 12 is an illustration for explaining distribution transferaccording to the first embodiment of the present invention.

FIGS. 13(a) and 13(b) are illustrations for explaining a transferringmethod of changing a transmission interval according to the firstembodiment of the present invention.

FIGS. 14(a) and 14(b) are illustrations for explaining a method ofchanging a unit data volume to be transmitted from a handover addressednode to a mobile unit according to the first embodiment of the presentinvention.

FIGS. 15(a) and 15(b) are illustrations for explaining a method ofadding a data transfer transport channel according to the firstembodiment of the present invention.

FIGS. 16(a) to 16(d) are illustrations for explaining a transferringmethod of changing a structure of a subchannel according to the firstembodiment of the present invention.

FIG. 17 shows an example of a sequence for explaining a transferringmethod based on resource allocation request according to the firstembodiment of the present invention.

FIG. 18 shows an example of a sequence for explaining a transferringmethod based on distribution transfer according to the first embodimentof the present invention.

FIG. 19 shows an example of a sequence for explaining a method ofchanging a transmission interval/information volume, adding a transportchannel and changing a structure of a subchannel according to the firstembodiment of the present invention.

FIGS. 20(a) and 20(b) are illustrations for explaining a first packettransferring method according to a second embodiment of the presentinvention.

FIG. 21 is an illustration for explaining a second packet transferringmethod according to the second embodiment of the present invention.

FIGS. 22(a) and 22(b) are illustrations for explaining a third packettransferring method according to the second embodiment of the presentinvention.

FIG. 23 is an illustration for explaining a fourth packet transferringmethod according to the second embodiment of the present invention.

FIGS. 24(a) and 24(b) are illustrations for explaining a fifth packettransferring method according to the second embodiment of the presentinvention.

FIGS. 25(a) and 25(b) are illustrations for explaining a first frameformat according to the second embodiment of the present invention.

FIGS. 26(a) and 26(b) are illustrations for explaining a second frameformat according to the second embodiment of the present invention.

FIGS. 27(a) and 27(b) are illustrations for explaining a third frameformat according to the second embodiment of the present invention.

FIGS. 28(a) and 28(b) are illustrations for explaining a fourth frameformat according to the second embodiment of the present invention.

FIG. 29 shows an example of a sequence for explaining a residual packettransferring method based on encapsulation according to the secondembodiment of the present invention.

FIG. 30 is an illustration for explaining a method of giving headerinformation to transfer data through the use of an association tableaccording to the second embodiment of the present invention.

FIG. 31 is an illustration for explaining a method of terminating aheader, given in a handover addressing node, in a handover addressednode according to the second embodiment of the present invention.

FIG. 32 is an illustration of an example of a sequence for explaining aresidual packet transferring method based on re-affixation of a protocolheader according to the second embodiment of the present invention.

FIGS. 33(a) and 33(b) are illustrations for explaining a differentpacket transferring method according to the second embodiment of thepresent invention.

FIGS. 34(a) and 34(b) are illustrations for explaining a differentpacket transferring method according to the second embodiment of thepresent invention.

FIGS. 35(a) and 35(b) are illustrations for explaining a differentpacket transferring method according to the second embodiment of thepresent invention.

FIG. 36 shows an example of a sequence for explaining a pattern Daccording to the second embodiment of the present invention.

FIG. 37 shows an example of a sequence for explaining an arbitrationmethod using a header re-affixation and a resource allocation requestaccording to the second embodiment of the present invention.

FIG. 38 is a schematic illustration of a configuration of a W-CDMAsystem.

FIG. 39(a) is an illustration of a state before handover.

FIG. 39(b) is an illustration of a state after handover.

FIG. 40 is an illustration for explaining DSCH.

BEST MODE FOR CARRYING OUT THE INVENTION

(A) Description of First Embodiment of the Present Invention

An embodiment of the present invention will be described hereinbelowwith reference to the drawings.

FIG. 1 is an illustration of a configuration of an essential part of aW-CDMA system to which the present invention is applied. A W-CDMA system50 shown in FIG. 1 is a mobile communication system designed toimplement a packet transferring/transmitting method according to thepresent invention for conducting the transmission/reception oflarge-capacity data such as voice, still image and moving image betweena network and a mobile unit, and is made up of a core network (CN) 100,radio network controllers (RNC) 2-0, 2-1, base stations (BTS) 3-0 to 3-5and a mobile unit (UE) 4. This W-CDMA system 50 includes a large numberof nodes which are omitted from the illustration.

(1-1) Core Network 100 and Exchange 1

The core network 100 is a network in which a line exchange, not shown, apacket exchange and a large number of upper nodes are mutually connectedto transmit high-speed and large-capacity packets and is equipped withan exchange 1 having a packet switching function.

When transmission/reception data is HS-DSCH data or DSCH data, each ofthe upper nodes corresponds to the RNC 2-0, 2-1 or the exchange 1, andeach lower node corresponds to the base station 3-0 to 3-5 or the RN2-0, 2-1 (see FIG. 40 mentioned later.

FIG. 2 is a schematic block diagram showing the exchange 1 according toa first embodiment of the present invention. The exchange 1 shown inFIG. 2 is made to transmit a plurality of new packets to the mobile unit4 from a different network other than the core network 100 and iscomposed of a line terminating unit 1 b, a control unit 1 a and aswitching unit 1 c.

The line terminating unit 1 b is for conducting transmission/receptionof data or a packet with respect to a different upper node (for example,the exchange 1 itself or an upper node other than the RNC 2-0, 2-1) or alower node (for example, the base station 3-0 to 3-5 or the RNC 2-0,2-1) and terminating it, and further for controlling a flow of dataunder flow control from a lower node.

Moreover, the switching unit 1 c is for switching a line with respect toan upper node or a lower node.

Still moreover, the control unit 1 a is for controlling the switchingunit 1 c on the basis of a control signal from an upper node or a lowernode.

Thus, the exchange 1 transfers a header-added packet, received from adifferent network other than the core network 100 or from the mobileunit 4, to the RNC 2-0, 2-1 or the core network 100 on the basis of itsaddress.

(1-2) RNC 2-0, 2-1

Each of the RNCs 2-0 and 2-1 has a function to terminate a radioprotocol prescribed in 3GPP or the like and a function to conduct packettransfer, control of the base stations 3-0 to 3-5, channel allocation,handover, origination/destination connection and others. Moreover, eachof the RNCs 2-0 and 2-1 also has a function to control the transmissionof DSCH data and HS-DSCH data according to a transmission suspension(transmission suspending message) or a start request (start requestingmessage) from the base stations 3-0 to 3-5.

In the following description, unless otherwise specified particularly,the handover signifies switching a transport channel (TrCH) from, forexample, the base station 3-1, with which the mobile unit 4 makes acommunication before the handover, to, for example, the base station 3-2with which the mobile unit 4 makes a connection after the handover.

(1-3) Base Station 3-0 to 3-5

(1-3-1) About Handover Addressing Node and Handover Addressed Node

Each of the base stations 3-0 to 3-5 is capable of terminating a radioprotocol prescribed in 3GPP or the like and functions as a logical node(Node B) for a radio link of the mobile unit 4 existing within cells110-0 to 110-5. Each of the base stations 3-0 to 3-5 has a datatransferring function to transfer buffered DSCH data or HS-DSCH datafrom a handover addressing node to a handover addressed node undercontrol of the exchange 1.

For convenience of the following description only, unless otherwisespecified particularly, the base stations 3-1 and 3-2 function as ahandover addressing node and a handover addressed node for the mobileunit 4, respectively. In this case, the handover addressing node is forconducting the transmission/reception of a packet with respect to themobile unit 4 before the handover, while the handover addressed node isfor transmitting a plurality of new packets, directed from the exchange1 to the mobile unit 4, to the mobile unit 4 before the handover.Incidentally, each of the base stations 3-3 to 3-5 can also function asa handover addressing node or a handover addressed node.

For suspending new packet transmission from the exchange 1 at thebuffering of data to be transmitted from the exchange 1 to the mobileunit 4, the base station 3-1 functioning as a handover addressing nodetransmits a transmission suspending request to the exchange 1 until thedata to be transmitted falls into a vacated condition. Moreover, in thebase station 3-1, when the data to be transmitted falls into a vacatedcondition, a transmission start request for the notification on thebuffer vacated condition is transmitted to the exchange 1.

In addition, when the data to be transmitted from the exchange 1 to themobile unit 4 is buffered, the base station 3-1 transfers the buffereddata to the base station 3-2 functioning as a handover addressed node.On the other hand, the base station 3-2 has an arbitration function toreceive the transferred data and data newly transmitted from theexchange 1 side and transmit these received data to the mobile unit 4while arbitrating them.

(1-3-2) Configuration of Base Stations 3-0 to 3-5

Each of the base stations 3-0 to 3-5 has a radio transmission function(modulation, code spread, radio frame transmission and others) on apacket transmitted from the RNCs 2-0 and 2-1, a radio reception function(radio frame reception, de-spread, demodulation and others) and a normalmonitoring function for using situations of a plurality of radioresources.

FIG. 3 is a block diagram showing the base station 3-1 according to thefirst embodiment of the present invention. The base station 3-1 shown inFIG. 3 is composed of a receiving unit (first receiving unit) 2 a, aline terminating unit (first line terminating unit) 2 b, a call controlunit (first call control unit) 2 c, an ARQ control unit (firstretransmission control unit) 2 d, an ARQ terminating unit (first ARQterminating unit) 2 e and a transmitting unit (first transmitting unit)2 f.

In this configuration, the receiving unit 2 a is for receiving a radioframe from the mobile unit 4 to carry out the demodulation and decodeprocessing thereon. The transmitting unit 2 f carries out the encodingand modulation processing on transmission data and transmits it to themobile unit 4. Moreover, the transmitting unit 2 f is capable of giving,to the transmission data, a priority which will be mentioned later in apattern B.

The line terminating unit 2 b is for terminating data with respect tothe exchange 1 side or the base station 3-2, and is made to transmit ortransfer, to the exchange 1 side or the base station 3-2, the datatransferred from a data holding buffer 2 g provided in the ARQterminating unit 2 e. It is composed of a first line receiving unit 22 aand a first line transmitting unit 22 b.

The first line receiving unit 22 a is for receiving a packet from theexchange 1 side or the base station 3-2. A buffer 2 g holds the packetreceived by this first line receiving unit 22 a.

The first line transmitting unit 22 b is made to, on the basis of apacket volume retransmission-controlled by the ARQ control unit 2 dwhich will be mentioned later, transmit the packet held in the buffer 2g to the base station 3-2 serving as a handover addressed node withoutinterposing the exchange 1 or the RNC 2-0, 2-1, or to transmit it to thebase station 3-2 through the upper node (base station 3-2 or theexchange 1). This terminates the transmission/reception of data withrespect to the exchange 1 side or the mobile unit 4 side.

Moreover, the call control unit 2 c is for carrying out the handovercontrol on the basis of a call control signal received from the mobileunit 4.

Still moreover, the ARQ control unit 2 d is made to carry outretransmission control on a packet volume to be transferred on the basisof a resource capacity of the base station 3-2 included in the packetreceived by the first line receiving unit 22 a (line terminating unit 2b) and a packet residual value held in the buffer 2 g. Yet moreover, theARQ control unit 2 d is made to conduct operations for the start, changeand termination of an H-ARQ (Hybrid-Auto Repeat Request) protocol. ThisH-ARQ is a name of the ARQ protocol prescribed in HS-DSCH.

As well known, the ARQ signifies a method of retransmitting data, lostdue to error in a radio zone or the like, under retransmission controlfor assuring the integrity of data, and H-ARQ depicts ARQ operating at ahigh speed. The transmission-waiting data held in the buffer 2 g becomestransferable to the line terminating unit 2 b according to aninstruction outputted from the ARQ control unit 2 d to the ARQterminating unit 2 e. This enables implementing the control on flow ofdata through the use of flow control.

In addition, the ARQ terminating unit 2 e is for terminating the ARQprotocol and for receiving new data from the exchange 1 or the RNC 2-0,2-1 and transferred data from the handover addressing node (base station3-2) to arbitrate and encapsulate the received data.

The line terminating unit 2 b, the call control unit 2 c, the ARQcontrol unit 2 d and the ARQ terminating unit 2 e cooperate with eachother, which provides a function as a transmitting means (2 b, 2 c, 2 d,2 e).

Thus, owing to the H-ARQ, the information data and the error correctiondata are independently transmittable and the number of times ofretransmission is reducible. Incidentally, the ARQ control unit 2 d canalso employ the normal ARQ.

FIG. 4 is a block diagram showing the base station 3-2 according to thefirst embodiment of the present invention. The base station 3-2 shown inFIG. 4 is composed of a receiving unit (second receiving unit) 3 a, aline terminating unit (second line terminating unit) 3 b, a call controlunit (second call control unit) 3 c, an ARQ control unit (secondretransmission control unit) 3 d, an ARQ terminating unit (second ARQterminating unit) 3 e and a transmitting unit (second transmitting unit)3 f which have the same functions as those of the receiving unit 2 a,the line terminating unit 2 b, the call control unit 2 c, the ARQcontrol unit 2 d, the ARQ terminating unit 2 e and the transmitting unit2 f provided in the base station 3-1, respectively.

The line terminating unit 3 b is for terminating data between the hostside exchange 1 and the lower side base station 3-1, and is composed ofa second line receiving unit 33 a and a second line transmitting unit 33b. The second line receiving unit 33 b is made to receive a plurality ofpackets from the host side exchange 1 and the lower side base station3-1. The second line transmitting unit 33 b is made to implement theretransmission control on the plurality of packets, received in thesecond line receiving unit 33 b, in the ARQ control unit 3 d which willbe mentioned later. Moreover, the ARQ control unit 3 d is made to carryout the retransmission control on the plurality of packets received bythe second line receiving unit 33 b.

The transmitting unit 3 f is made to give a retransmission controlheader, undergoing the retransmission control in the ARQ control unit 3d, to the plurality of packets received by the second line receivingunit 33 a and transmit a radio frame with this header to the mobile unit4. The header giving to the transmitting unit 3 f will be explained inpatterns B and C which will be mentioned later.

The call control unit 3 c, the ARQ control unit 3 d, the ARQ terminatingunit 3 e and the transmitting unit 3 f cooperate with each other, whichprovides a function as a transmitting means (3 c, 3 d, 3 e, 3 f).

The description of the functions other than these will be omitted foravoiding repeating explanation. Moreover, the configurations of the basestations 3-0 and 3-3 to 3-5 are the same as that of the base station3-1, and the description thereof will be omitted for avoiding repeatedexplanation.

As described above, the W-CDMA system 50 has a function to switch atransmission path of data, which is from the upper node (an upperapparatus) to the mobile unit 3, from the transmission from the handoveraddressing node 2 to the transmission from the handover addressed node3. In addition, the handover addressing node 2 is equipped with atransferring means (2 b, 2 c, 2 d, 2 e) to transfer the data, addressedto the mobile unit 4 and left in the handover addressing node 2, to thehandover addressed node 2 at this switching, and the handover addressednode 3 is equipped with a transmitting means (3 c, 3 d, 3 e, 3 f) totransmit the data received through this transferring and the data froman upper node to the mobile unit 4.

(1-4) Mobile Unit (UE) 4

The mobile unit 4 has a function to make radio communication with thebase stations 3-0 to 3-5, a function to make transmission/reception ofdata on communication, management and control and a function to conductan H-ARQ operation, and it is a portable telephone or portable radioterminal, a user manipulates.

FIG. 5 is a block diagram showing the mobile unit 4 according to thefirst embodiment of the present invention. The mobile unit 4 shown inFIG. 5 is composed of an antenna 4 f, a receiving unit 4 a, an ARQterminating unit 4 b, a call control unit 4 c, an ARQ control unit 4 dand a transmitting unit 4 e.

The antenna 4 f is for making transmission/reception of a radio frame.The receiving unit 4 a is for receiving a radio frame from the basestations 3-0 to 3-5 to conduct the demodulation and decoding processingthereon. The ARQ terminating unit 4 b is for terminating the ARQprotocol. The call control unit 4 c is for conducting the handoverprocessing on the basis of a call control signal received from the basestations 3-0 to 3-5. The ARQ control unit 4 d is for conducting thestart of the ARQ protocol, modulation and termination under control fromthe call control unit 4 c. The transmitting unit 4 e is for conductingthe encoding and modulation processing on a call control signal, userdata and ACK/NACK of ARQ to transmit them to the base stations 3-0 to3-5.

(1-5) Cells 110-0 to 110-5 (see FIG. 1)

Each of the cells 110-0 to 110-5 represents, between the mobile unit 4and the base station 3-0 to 3-5, a schematic range in which ahigh-quality radio frame is transmittable/receivable, and the range ofeach of the cells 110-0 to 110-5 almost overlaps with the range of theadjacent cell 110-0 to 110-5. When moving to the overlapping range, themobile unit 4 makes the transmission/reception of the same data withrespect to the adjacent base station 3-0 to 3-5, thereby achieving thesoft handover.

(1-6) Transmission Line

The nodes 101, 102-0 to 102-n, 103-0 to 103-n and 104 are physicallyconnected through an ATM transmission line, and an interface between thenodes is prescribed in a specification. Concretely, the interfacesbetween the RNCs 102-0 to 102-n and the exchanger 1 are an ATMtransmission line which is referred to as Iu, and the interfaces betweenthe RNCs 102-0 to 102-n are referred to as Iur. The interfaces betweenthe RNCs 102-0 to 102-n and the base stations 103-0 to 103-n are an ATMtransmission line which is referred to as Iub, and the interface betweenthe base stations 103-0 to 103-n and the mobile unit 104 is referred asto Uu.

(1-7) New Packet and Transfer Packet

Each of the exchange 1 and the mobile unit 4 fragments large-capacityaudio data, text data, image data and others into a large number of finedata, and transmits the fragmented data without packeting or transmits alarge number of packets by means of packeting.

Therefore, with respect to the downlink, the exchange 1 continuouslytransmits audio data, text data and others to the same mobile unit 4 ata constant time interval while segmenting them, and transmits differentkinds of text data and others to a different mobile unit (not shown).This also applies to the uplink.

Concretely, in a user telephone (not shown) in the core network 100,voice and others are encoded at a predetermined time interval, and theencoded audio data is fragmented into, for example, 1000 data andheaders having serial numbers counted up from 1 in order are given tothe 1000 data, respectively, to produce 1200 packets.

Thus, with respect to the packets with the serial numbers, for example,each of the ARQ control units 2 d, 3 d provided in the RNCs 2-0 and 2-1records the serial numbers of the packets, which has been receivednormally, and the serial number of the packets, which has not beenreceived normally. Moreover, the ARQ control units 2 d and 3 d issue arequest for retransmission to the user telephone in the core network 100and, when receiving the retransmitted two packets, recognize thereception of all the packets. Subsequently, the ARQ unit extracts thedata included in the 1200 packets to assemble a voice, a text file orthe like within a constant period of time as one unit of userinformation and hands it over to an upper layer. It is also appropriatethat, in place of the layer 2 ARQ unit, an upper layer equal to orhigher than layer 3 performs this assembling.

In the following description, audio data, text data or the like isreferred to as a new packet as unit of transmission/reception. That is,each new packet represents one unit of user information composed of alarge number of packets. Moreover, each packet is once buffered in theRNC 2-0, 2-1 as will be mentioned in detail later before beingtransmitted to the mobile unit 4. Through the use of the serial numbergiven to each packet, each packet is managed in terms ofreception/non-reception in an ARQ (Auto Repeat Request: automaticretransmission control) provided in each node which is made totransmit/receive or repeat the packet. In this case, it is preferable toemploy H-ARQ having a processing speed higher than that of the ARQ.

The configuration shown in FIG. 2 is the same as that of a secondembodiment which will be described later.

(2) Referring to FIG. 6, a description will be given hereinbelow of apacket transferring/transmitting method according to the presentinvention.

FIG. 6 is an illustration for explaining a packettransferring/transmitting method according to the first embodiment ofthe present invention, and shows a model which is a simplification ofthe configuration shown in FIG. 6. An upper node shown in FIG. 6corresponds to the exchanger 1 in the case of an HS-DSCH channel.Moreover, in the upper node 1, the transmission of user data and thehandover control are implemented, and in a handover addressing node 3(base station 3-1) and a handover addressed node 3 (base station 3-2),an uplink packet and a downlink packet are transmitted/received withrespect to the upper node 1, and a radio frame is transmitted withrespect to the mobile unit 4 through the use of an ARQ communicationprotocol. The employment of this ARQ assures the perfect datacommunication between the handover addressing node 2/the handoveraddressed node 3 and the mobile unit 4.

In addition, in the handover addressed node 3, a conversion is made on adata format between a transmission zone and a radio zone. In this case,the ARQ protocol in the handover addressing node 2 and the handoveraddressed node 3 corresponds to an RLC (Radio Link Control) protocol.The mobile unit 4 makes the transmission/reception of a radio frame withrespect to the handover addressing node 2 and the handover addressednode 3, and carries out the handover.

In the following, unless otherwise specified particularly, the mobileunit 4 carries out the handover due to walking, vehicle or train in astate where it makes packet transmission/reception with respect to thehandover addressing node 2 and carries out the packettransmission/reception with respect to the handover addressed 3.

(2-1) Packet Transferring/Transmitting Method According to the PresentInvention.

The packet transferring/transmitting method according to the presentinvention is for use in the W-CDMA system 50 including the upper node 1made to transmit a plurality of packets addressed to the mobile unit 4,the handover addressing node 2 made to transmit a plurality of packetsaddressed to the mobile unit 4 and the handover addressed node 3 made totransmit a plurality of packets addressed to the mobile unit 4, and theupper node 1 determines the implementation of the handover(determination step). Moreover, the handover addressing node 2transfers, of the plurality of packets, a non-transmitted residualpacket(s) to the handover addressed node 3 (transfer/transmission step).Still moreover, preferably, the determination (determination step) ofthe implementation of the handover is based upon the reception of ahandover request transmitted from the mobile unit 4 or a radio situationreport from the mobile unit 4.

(2-2) Implementation Patterns A to D

Among the implementation patterns of the packettransferring/transmitting method according to the present invention,there are four types of patterns A to D as will be mentionedhereinbelow, and these patterns A to D are classified into the patternsA, C and the patterns B, D according to modes in which the handoveraddressing node 2 transfers/transmits packets to the handover addressednode 3.

(2-3) Relationship Between Implementation Patterns A to D and ThisPacket Transferring/Transmitting Method

The first packet transferring/transmitting method (pattern A, C) is amethod of suspending the transmission of a new packet from the uppernode 1 to the handover addressed node 3. That is, the handoveraddressing node 2 (or the upper node 1 itself) suspends the transmissionof a new packet from the upper node 1 (suspension step) and, while thetransmission of the new packet is in a suspended condition, the handoveraddressing node 2 transfers a residual packet(s) to the handoveraddressed node 3 (first residual packet transferring step). Moreover,when the residual packet is transferred in the first residual packettransferring step, the handover addressing node 2 (or the upper node 1itself) resumes the transmission of the new packet from the upper node 1(resumption step), and the upper node 1 transmits the new packet to thehandover addressed node 3 (new packet transmitting step)

The second packet transferring/transmitting method (patterns B and D) isa method of continuing the transmission of a new packet from the uppernode 1 to the handover addressed node 3 so that the handover addressednode 3 carries out the arbitration between the packet transferred fromthe handover addressing node 2 and the new packet transmitted from theupper node 1. That is, the handover addressing node 2 transfers aresidual packet to the handover addressed node 3 (second residual packettransferring step), and the upper node 1 transmits a new packet to thehandover addressed node 3 (new packet transmitting step). Moreover, thehandover addressed node 3 carries out the arbitration between the packettransferred in the second residual packet transferring step and thepacket transmitted in the new packet transmitting step (arbitrationstep).

In addition, the patterns C and D are a method of encapsulatingtransferred data in each of the patterns A and B. Therefore, thepatterns A to D are roughly classified into two patterns×two patterns.In other words, the patterns A and B correspond to cases ofsuspending/non-suspending the new packet transmission from the uppernode 1 while, at the handover, the data left in the handover addressingnode 2 without being transmitted is transferred to the handoveraddressing node 3. The patterns C and D correspond to cases of, whendata is transferred, encapsulating/non-encapsulating the transferreddata with it being regarded as a portion of the new packetcommunication.

In this connection, the patterns A to D have two patterns addedaccording to a residual packet transferring method. Concretely, theseadded two patterns correspond to a case in which it is conducted in amanner such that a direct transferring line is set between the uppernode 1 and the handover addressing node or the handover addressed node 3and a case in which it is conducted by way of the upper node 1. In thefollowing explanation, they will be handled as extension patterns fromthe aforesaid four patterns.

(2-4) Description of DSCH and HS-DSCH

FIG. 40 is an illustration for explaining DSCH. The DSCH shown in FIG.40 is a downlink channel a plurality of mobile units 4 (for example,user 1 to user 3) share, which achieves the service efficiency of radioresources. Moreover, the HS-DSCH (not shown) signifies a high-speeddata-transmittable DSCH. The specifications of the DSCH and HS-DSCH areprescribed in the described TS25.435/427/425 and the describedTR25.835/837/848/855/877/950.

The units for terminating these DSCH data and HS-DSCH data are differentfrom each other. In the W-CDMA system 50, the DSCH data is terminated inthe RNC 2-0, 2-1, and an upper node and a lower node correspond to anexchange and an RNC, respectively. Moreover, in a system employing theDSCH, all the functions such as an RLC (Radio Link Control) protocolprocessing concentrate on the RNC 2-0, 2-1. The principal function ofthe base stations 3-0 to 3-5 is the switching between a transmissionline zone and a radio zone (not shown for simplicity).

On the other hand, the HS-DSCH data is terminated in the base stations3-0 to 3-5, and an upper node and a lower node correspond to the RNCs2-0, 2-1 and the base stations 3-0 to 3-5, respectively. In an HS-DSCHsystem, an ARQ function is provided in the base station 3-0 to 3-5 closeto the mobile unit 4. This ARQ function uses an H-ARQ protocol. ThisH-ARQ is a method of retransmitting data lost due to error in a radiozone under retransmission control for assuring the integrity of data.

A description will be given hereinbelow of a case employing the HS-DSCHwhere upper nodes and lower nodes are the RNCs 2-0, 2-1 and the basestations 3-0 to 3-5, respectively. The present invention can be carriedout even in the case of the employment of DSCH.

(2-5) Description of Outline of Patterns A to D

Furthermore, referring to FIG. 6, a description will be given of asequence for a control signal and user data between nodes.

The respective patterns will be described in the following order of A toD.

-   -   A. The transmission of a new packet is once suspended during the        transfer of a residual packet and data to be transferred is not        encapsulated.    -   B. A new packet is transmitted even during the transfer of a        residual packet and data to be transmitted is not encapsulated.    -   C. The transmission of a new packet is once suspended during the        transfer of a residual packet and data to be transmitted is        encapsulated.    -   D. A new packet is transmitted even during the transfer of a        residual packet and data to be transferred is encapsulated.

A description will be given hereinbelow of each pattern.

(3) Description of Pattern A

FIGS. 7(a) to 7(e) are illustrations for explaining an operation of thepattern A according to the first embodiment of the present invention.

When the mobile unit 4 shown in FIG. 7(a) starts to move, the handoveraddressing node 2 detects the quality degradation. Moreover, thehandover addressing node 2 shown in FIG. 7(b), for transferring aresidual packet, makes the upper node 1 suspend a new packettransmission. Subsequently, the handover addressing node 2 transfers aresidual packet to the handover addressed node 3 (see FIG. 7(c))designated by the upper node 1. When the residual packet transferringreaches completion, the handover addressing node 2 shown in FIG. 7(d)transmits a resume request for resuming the new packet transmission tothe upper node 1. Following this, the upper node 1 shown in FIG. 7(e)transmits a new packet to the handover addressed node 3.

Furthermore, referring to an example of a sequence shown in FIG. 8, adescription will be given of an operation of the same pattern A. In FIG.8, HO, HO Addressing Lower Node, HO Addressed Lower Node and Upper Noderepresent handover, handover addressing node, handover addressed nodeand the upper node, respectively, and this also applies to the drawingsto be referred to for the following description. Moreover, (3-1) to(3-9) correspond to the reference numerals 1 to 9 in FIG. 8,respectively.

(3-1) The upper node 1 shown in FIG. 8 monitors the quality of a signalreceived from the mobile unit 4, and detects the degradation thereof andstarts the implementation of the handover. The start of the handoverdepends upon, in addition to a handover request from the mobile unit 4,a decision in the upper node 1 based on a radio situation report on themobile unit 4 itself which is to be transmitted from the mobile unit 4to the upper node 1.

In this case, the mobile unit 4 measures a radio situation around theposition of the mobile unit 4 itself at all times and reports this radiosituation to the upper node 1, and the upper node 1 transmits aninstruction on the handover to this mobile unit 4. As an example ofradio situation report, the upper node 1 receives, at all times,information indicative of whether the actual measurement value isimproved or which of radio areas is improved in quality, or informationindicative of which of radio areas is degraded in quality. Moreover, theupper node 1 makes a comparison between the information transmitted fromthe mobile unit 4 and the radio intensity information held therein inadvance to make a determination as to whether or not the electric fieldstrength permits the radio communication. Still moreover, the upper node1 selects an appropriate one of the radio areas around the mobile unit 4and notifies the selected area to the handover addressing node 2. Thus,the handover addressing node 2 can seize the handover addressed node 3.

(3-2) For requesting a resource securement for a communication with themobile unit 4 which conducts the handover, the upper node 1 transmits ahandover preparation request to the handover addressed node 3 (this alsoapplies to the other drawings). The handover addressed node 3 secures aresource in response to this request. Moreover, in a case in which achannel between the upper node 1 and the handover addressed node 3 isnot set yet (in the case of the first message transmission/reception),the handover addressed node 3 newly activates a shared channel (sharedTrCH: shared transport channel) with respect to the upper node 1 andprepares the handover through the activation of the shared transportchannel and transmits the handover preparation completion to the uppernode 1. If there is a channel already activated, it adds a user.

(3-3) The upper node 1 permits the handover addressing node 2 toimplement the handover. Upon receipt of this permission (handoverimplementation permission), the handover addressing node 2 transmits asuspend request to the upper node 1 to suspend the transmission of a newpacket.

Incidentally, in place of the transmission of the suspend request fromthe handover addressing node 2, it is also appropriate that the uppernode 1 itself suspends the transmission of a new packet with referenceto the time of the handover implementation permission.

(3-4) The upper node 1 transmits a handover instruction (handoverimplementation request) to the mobile unit 4. In accordance with thisinstruction, the mobile unit 4 starts the implementation of the handoverand resets the held contents of the ARQ control unit 4 d (see FIG. 5).Moreover, the mobile unit 4 shifts to the handover addressed node 3 andsecures a communication channel.

(3-5) The upper node 1 sets a bearer channel to transfer data left inthe handover addressing node 2 to the handover addressed node 3. Thisbearer channel can be set to make direct communication between thehandover addressing node 2 and the handover addressed node 3, and it canalso be set through the upper node 1.

(3-6) The upper node 1 makes a request for the transfer of a residualpacket to the handover addressing node 2 (expressed as held datatransferring instruction). According to this request, the handoveraddressing node 2 transfers a residual packet (user data) to thehandover addressed node 3 through the use of the bearer channel set in(3-5). The handover addressed node 3 transfers the residual packet tothe mobile unit 4 in a state where the residual packet from the handoveraddressing node 2 is monitored by the ARQ control unit 4 d .

(3-7) When the transfer of the residual packet reaches completion, thehandover addressing node 2 cancels the shared channel and the releasesthe resource secured by the mobile unit 4 which has conducted thehandover, and transmits a resume request to the upper node 1. Althoughin the sequence shown in FIG. 8 the handover addressing node 2 outputsthe resume request, it is also appropriate that the upper node 1 itselfmonitors the completion of the transfer and performs the resumption whendetecting the completion.

(3-8, 3-9) Upon receipt of the resume request, the upper node 1 releasesthe bearer channel set for transferring the residual packet and resumesthe transmission of a new packet to the handover addressed node 3.

Thus, the W-CDMA system 50 suspends the transmission of data from theupper node to the handover addressed node 3 during the transfer by thetransferring means (2 b, 2 c, 2 d, 2 e).

In addition, since the transmission of a new packet is once suspendedduring the transfer of a residual packet in this way, the number ofusers to be accommodated is maintainable while securing a widebandwidth, and the sharing of a line is efficiently feasible at thehandover.

(4) Description of Pattern B

FIGS. 9(a) to 9(c) are illustrations for explaining the pattern B. Whenthe mobile unit 4 shown in FIG. 9(a) starts to move, the handoveraddressing node 2 detects the quality degradation. The handoveraddressing node 2 shown in FIG. 9(b) transfers a residual packet throughthe upper node 1 to the handover addressed node 3. In this case, theupper node 1 continues the transmission of a new packet, and thehandover addressed node 3 receives the transferred packet and the newpacket. Moreover, after the transfer of the residual packet reachescompletion, the transmission of a new packet from the upper node 1 shownin FIG. 9(c) to the handover addressed node 3 continues.

In the packet transferring/transmitting method (transfer/transmissionstep) according to the pattern B, the handover addressing node 2 or theupper node 1 secures a resource for holding a residual packet in thehandover addressed node 3 and transmits a new packet. Concretely, thehandover addressing node 2 having the residual packet transmits aresource allocation request to the handover addressed node 3 which formsa transferring destination. At this time, the handover addressing node 2makes a request to the handover addressed node 3 so as to secure aresource having a capacity sufficient for the transmission of the entireresidual packet. In this connection, since the handover addressing node2 transmits the transferred data with a priority higher than that of anew packet, it is preferable that the transmitting unit 2 f (see FIG. 3)allocates a priority and requests a resource.

Thus, the new packet is continuously transmitted even while the residualpacket is transferred. Moreover, the transferred data is transferredwithout being encapsulated.

(4-1) Description of Transferring Method

In (4-1-1) to (4-1-3), a description will be given hereinbelow of thetransfer between a handover addressing node and a handover addressednode, and in (4-1-4), a description will be given of the transferbetween a handover addressed node and a mobile unit.

The following methods are employable as the transferring method and willbe described with reference to FIGS. 10 to 16. Incidentally, acombination of the transferring methods shown in FIGS. 10 to 16 isfeasible.

(4-1-1) FIG. 10 is an illustration for explaining an arbitration methodbased on a resource allocation request according to the first embodimentof the present invention. In FIG. 10, the handover addressing node 2makes a request to the handover addressed node 3 for a report on thepresent resource vacancy situation (resource allocation request).Moreover, the handover addressed node 3 examines the free capacity ofthe buffer 3 g and notifies a free resource allocation (resourceallocation permission). The handover addressing node 2 transfers thetransferable data of the residual packet, the handover addressing node 2itself holds, according to the resource vacancy situation (user datatransfer). The handover addressing node 2 repeatedly conducts thistransfer until the residual packet runs out. This enables the efficientuse of the resource.

(4-1-2) FIG. 11 is a flow chart for explaining a transferring methodbased on the measurement of a free buffer capacity according to thefirst embodiment of the present invention. In the packettransferring/transmitting method shown in FIG. 11, the handoveraddressing node 2 transmits a “buffer vacancy capacity measurementrequest” message to the handover addressed node 3, and the handoveraddressed node 3 measures its own reception buffer vacancy capacity(step A1) and transmits the measurement result as a “measurement report”message to the handover addressing node 2.

Subsequently, when receiving this “measurement report” from the handoveraddressed node 3, the handover addressing node 2 makes a decision as towhether or not a resource vacancy capacity is left in the handoveraddressed node 3 (step A2). If the vacancy capacity runs short, theoperational flow goes through the NO route to return to the beginning ofthe processing. On the other hand, if the vacancy capacity is left, theoperational flow goes through the YES route, and the handover addressingnode 2 makes a decision that the vacancy capacity is sufficient and,hence, determines a pattern of a residual packet transmitting method andtransfers the data corresponding to the vacancy capacity to the handoveraddressed node 3 (vacancy capacity data transfer) . At this time, on thebasis of a decision instruction from the upper node 1 or the basestation (before and after the handover), the handover addressing node 2determines one of the collective transmission of data after theadjustment on the number of divisions and the division transmission.

In a step A3, the handover addressed node 3 puts the transferred data ina reception buffer area on which a detection has been made as vacancy inthe previous measurement, with the data being transferred to the buffer,provided in the interior of the handover addressed node 3 itself,according to stored data volume, storage time and others.

Thus, the handover addressing node 2 according to the present inventiontransfers a transferable portion of the residual packet(s) on the basisof the resource capacity measured in the measurement step (schedulingstep).

(4-1-3) Description of Distribution Transfer

This distribution transfer signifies a method in which the handoveraddressing node 2 transmits a residual packet to the handover addressednode 3 and the handover addressed node 3 transmits data to the mobileunit 4 in the order of arrival.

FIG. 12 is an illustration for explaining the distribution transferaccording to the first embodiment of the present invention. In FIG. 12,the handover addressing node 2 is made to, instead of making a requestfor the notification on the resource situation to the handover addressednode 3, divide (distribute) and transmit a residual packet by a smallvolume for transmitting the residual packet in the intervals of thetransmission of a new packet.

In this pattern transferring/transmitting step, the handover addressingunit 2 divides a residual packet into a plurality of packets having adata volume corresponding to the communication rate in a radio zone(division step) and transmits the plurality of divided packets, obtainedby the division in the division step, to the handover addressed node 3(division transmission step) . Moreover, the handover addressed node 3transmits a plurality of packets including mixedly the plurality ofdivided packets transmitted in the division transmission step and aplurality of new packets transmitted from the upper node 1 to the mobileunit 4 in the order of reception (order-of-arrival transmission step).

Thus, the handover addressing node 2 transmits a residual packet in astate distributed through the use of regular transmission orrandom-interval transmission, and the handover addressed node 3transmits the packet, first received, to the mobile unit 4 irrespectiveof the new packet or the residual packet.

(4-1-4) Method for Data Transmission Between Handover Addressed Node 3and Mobile Unit 4

(4-1-4-1) Transferring Method for Changing Radio Transmission Interval(Transmission Interval)

In this transferring method, the handover addressing node 2 changes thetransmission interval in the middle of data (packet) transfer whentransmitting the plurality of divided packets to the handover addressednode 3.

FIGS. 13(a) and 13(b)are illustrations for explaining a transferringmethod for changing the transmission interval according to the firstembodiment of the present invention. The transmission interval T shownin FIG. 13(a) is a transmission interval to be taken when data (packet)is not transferred from the handover addressing node 2 to the handoveraddressed node 3, and the data transmission interval from the handoveraddressed node 3 to the mobile unit 4 is constant. On the other hand, inthe middle of transfer, the handover addressed node 3 shown in FIG.13(b) reduces a new packet and a transfer packet transmission intervalto a time interval T′ and transmits the packet to the mobile unit 4. InFIG. 13(b) and FIG. 14(b), “new” and “transfer” represent a new packetand a transfer packet, respectively.

The new packet transmission interval is determined by the upper node 1,and the handover addressed node 3 receives a notification on atransmission interval through a transport channel change request fromthe upper node 1. Moreover, the transfer packet transmission interval isdetermined by the upper node 1 in the case of HS-DSCH, and it isdetermined by the handover addressing node 2 in the case of DSCH. Thisis because, in the case of HS-DSCH, the upper node 1 is the RNC 2-0, 2-1and carries out the call control on the base station 3-1, 3-2, andbecause, in the case of DSCH, the lower node is the RNC 2-0, 2-1 andcarries out the call control on the exchange 1 forming an upper node.

This transferring method enables efficient transmission of both thetransferred residual packet and new packet, which increases thecommunication rate. Moreover, since the data transmission interval whichis a factor of determination of the communication rate is changed inthis way, the communication rate is increasable.

Thus, the radio-transmittable information volume is increased or changedin accordance with an instruction from the upper node 1, which makes thecapacity of the buffer 3 g of the handover addressed node 3 constant andcontributes to the optimization of the radio resource.

(4-1-4-2) The handover addressed node 3 can also increase the unit datato be transmitted to the mobile unit 4.

FIGS. 14 (a) and 14 (b) are illustrations for explaining a method ofchanging a unit data volume to be transmitted from the handoveraddressed node 3 to the mobile unit 4 according to the first embodimentof the present invention. A transmission volume “1” for new datatransmission is set in the non-transferring case shown in FIG. 14(a),while a transmission volume “2” is set during the transferring as shownin FIG. 14 (b). That is, for making the transmission, the handoveraddressing node 2 changes the data volume (an increase from thetransmission volume “1” to the transmission volume “2”) in a unittransmission interval.

In other words, the difference from (4-1-4-1) is that, in the case of(4-1-4-1), the communication rate is increased by changing thetransmission interval, whereas in the arbitration method shown in FIG.14(b), the communication rate is increased by enhancing the data volumetransmittable at once without changing the transmission interval.Moreover, a combination of the case of (4-1-4-1) and this pattern isfeasible.

The handover addressed node 3 receives a notification on thetransmission interval through a transport channel change request fromthe upper node 1. Moreover, the transfer packet transmission interval isdetermined by the upper node 1 in the case of HS-DSCH, while it isdetermined by the handover addressing node 2 in the case of DSCH.

This also enables the simultaneous transmission of a residual packet anda new packet, thereby enhancing the communication rate.

(4-1-5) Method of Adding Data Transferring Transport Channel

FIGS. 15(a) and 15(b) are illustrations for explaining a method ofadding a data transferring transport channel according to the firstembodiment of the present invention. FIG. 15(a) shows a flow of userdata in the case of no transfer, and the handover addressing node 2 orthe handover addressed node 3 transmits user data through a transportchannel to the mobile unit 4.

FIG. 15(b) shows a case in the middle of the transfer, and the uppernode 1 additionally sets a transport channel, which is for transferringa residual packet from the handover addressing node 2, in a transportchannel for transmitting a new packet. An arbitration unit (MUX) 3 h isfor making the arbitration between transferred data from the handoveraddressing node 2 and new data from the upper node 1. The handoveraddressed node 3 determines the data to be transmitted through eachtransport channel, on the basis of an upper limit data rate in the caseof a combination of the data rate in each transport channel and both thechannels, a priority of each transport channel, or the like.

In the packet transferring/transmitting method according to the presentinvention, the upper node 1 secures the assignment of a separatetransfer channel from a portion of a transfer channel between thehandover addressed node 3 and the handover addressing node 2 on thebasis of a packet volume in a radio zone (channel setting step).

As one example of channel assignment, as shown in FIG. 15(b), thetransferred data transport channel and the new data transport channelare secured, and the transferred data and the new data aretransferred/transmitted through these two transport channels to thehandover addressed node 3. Moreover, the arbitration unit 3 h of thehandover addressed node 3 arbitrates the packets received through thesetwo types of transport channels.

In addition, the handover addressed node 3 carries out the scheduling onpacket transmission through the use of a partial separate transferchannel secured in the channel setting step and a new channel(scheduling step), and transmits a new packet and a residual packet tothe mobile unit 4 on the basis of the scheduling in the scheduling step(scheduling transmission step).

The handover addressed node 3 adds a residual transfer transport channelin accordance with an instruction from the upper node 1, and carries outthe scheduling to a transmission data volume, to be transmitted throughradio means to the mobile unit 4, with respect to both the transfertransport channel and the normal transport channel for transmitting thetransmitted packet to the mobile unit 4 according to the scheduling.

In addition, the arbitration unit 3 h shown in FIG. 15(b) provides twotypes of arbitration methods according to priority of a packet and, inthe two cases of a case in which the priority of the transfer data ishigher than that priority of the new data and a case in which thepriority of the transfer data and the priority of the new data are equalto each other, carries out the scheduling transmission or schedulingreception to transmit a packet to the mobile unit 4.

Incidentally, in the W-CDMA system 50, this scheduling is similar to thescheduling and priority control by TFCS (Transport Format CombinationSet) in an MAC (Media Access Control) layer.

Moreover, the upper node 1 can also assign a new channel instead ofassigning a transfer channel separately from a transfer channel.

(4-1-6) Method of Allocating or Adding ARQ Subchannel for Data Transfer

FIGS. 16(a) to 16(d) are illustrations for explaining a transferringmethod for changing a structure of a subchannel according to the firstembodiment of the present invention. FIG. 16(a) and FIG. 16(c) (which isthe same as FIG. 16(a)) shows a case in which data is not in the middleof transfer, and FIG. 16(b) and FIG. 16(d) show a case in which data isin the middle of transfer.

In these FIGS. 16(a) to 16(d), the handover addressed node 3 changes aframe format in a radio zone between it and the mobile unit 4.

The time for all of a subchannel 1 (Sub CH-1) to a subchannel n (SubCH-n) shown in FIGS. 16(a) and 16(b) corresponds to a waiting time to betaken from data transmission to arrival confirmation and is a time untilthe reception of ACK after packet transmission in a node which hastransmitted a packet. In the illustrations, n represents a naturalnumber. The subchannel n in the waiting time shown in FIG. 16(b) isassigned for transmitted data transmission.

In a regeneration method for an HS-DSCH channel or the like in theW-CDMA system 50, for simplifying are transmission protocol, a packettransmission side does not transmit the following data until receivingan arrival confirmation (ACK) from a receiving node. This regenerationmethod is such that the upper node 1 divides the aforesaid waiting timeinto a plurality of subchannels and transmits them separately andconcurrently.

The subchannel n+1 of the waiting time shown in FIG. 16(d) is assignedfor transfer data and the subchannel n thereof is assigned for new data,but it is different from the waiting time shown in FIG. 16(b). Forexample, the data transmitted through the subchannel 1 arrives at themobile unit 4 and this data undergoes the ARQ processing in the mobileunit 4. Therefore, a base station receives ACK from the mobile unit 4 ata time after the subchannel n.

For this reason, in the packet transmitting/transferring methodaccording to the present invention, the time from when a base stationtransmits the subchannel 1 until receiving the corresponding ACK isdivided into the subchannel 2 to the subchannel n as shown in FIG.16(d).

Accordingly, in the case of the use of a plurality of subchannels, thehandover addressed node 3 assigns a portion of subchannels for onlytransfer data from the handover addressing node 2 or adds a subchannel,thereby transmitting a new packet and transfer data concurrently.

Thus, a retransmission considering type frame format to beradio-transmitted is changed according to an instruction from the uppernode 1, which can make the capacity of the buffer 3 g of the handoveraddressed node 3 constant and contribute to the optimization of theradio resource.

(5) Description of Example of Operational Sequence of Pattern B

In this configuration, referring to FIGS. 17 to 19, a description willbe given hereinbelow of an example of a sequence for a transfer packettransmitting/transmitting method in which a new packet is transmittedeven during the transfer of a residual packet and the encapsulation isnot conducted. In FIGS. 17 to 19 , the names which are the same as thenames used above have the same or similar functions, and the descriptionwill be omitted for avoiding repeating.

(5-1) Transferring Method Based on Resource Allocation Request

FIG. 17 shows an example of a sequence for explaining a transferringmethod based on a resource allocation request according to the firstembodiment of the present invention, and (5-1-1) to (5-1-9) correspondto the reference numerals 1 to 9 in FIG. 17, respectively.

(5-1-1) The mobile unit 4 starts the handover due to the degradation ofquality of a signal received. The handover occurs according to adecision in the upper node 1 made on the basis of a request from themobile unit 4 or a radio situation report from the mobile unit 4. Inthis case, the upper node 1 determines the handover implementation (HOimplementation), and for starting the handover, the mobile unit 4transmits a handover preparation request to the handover addressed node3.

(5-1-2) The upper node 1 makes a request to the handover addressed node3 for the securement of a resource accommodating the mobile unit 4 whichcarries out the handover. Concretely, upon receipt of this request, inthe case of a first message transmission/reception between the uppernode 1 and the handover addressed node 3, the handover addressed node 3newly activates a shared channel and activates a shared transportchannel for the preparation of the handover and further transmits ahandover preparation completion to the upper node 1. If there is achannel already activated, it adds a user.

As this handover preparation, the handover addressed node 3 is made tosecure, as a resource, a shared channel for accommodating the mobileunit 4 which carries out the handover.

In addition, when receiving this completion, the upper node 1 notifies ahandover implementation permission to the handover addressing node 2 andtransmits a handover implementation request to the mobile unit 4.

(5-1-3) The upper node 1 permits the handover addressing node 2 toimplement the handover.

(5-1-4) The upper node 1 transmits a handover instruction (handoverimplementation request) to the mobile unit 4. The mobile unit 4 securesthe handover addressed node 3 and a communication channel in accordancewith this instruction.

(5-1-5) A bearer channel is set to transfer the data, left in thehandover addressing node 2, to the handover addressed node 3. Thisbearer channel can be set to make a direct connection between thehandover addressing node 2 and the handover addressed node 3 or it canalso be set to pass through the upper node 1.

(5-1-6) Moreover, the handover addressing node 2 transmits, to thehandover addressed node 3, a request for allocation of a resource neededfor the transmission of a residual packet. Upon receipt of this request,the handover addressed node 3 secures a resource corresponding to therequest and notifies the resource securement to the handover addressingnode 2.

(5-1-7) When receiving this resource securement notification, thehandover addressing node 2 starts to transfer the residual packet. Thehandover addressed node 3 transmits the transmitted residual packet anda new packet to the mobile unit 4 according to the assigned resource.

(5-1-8) When the transfer of the residual packet reaches completion, thehandover addressing node 2 releases the resource secured by the mobileunit 4 which has carried out the handover.

(5-1-9) The upper node 1 releases the bearer channel set for theresidual packet transfer.

Thus, the data residual is avoidable even in the case of the employmentof the variable communication rate and an increase in retransmission ispreventable.

(5-2) Arbitration Method Based on Distribution Transfer

FIG. 18 shows an example of a sequence for explaining a transferringmethod based on distribution transfer according to the first embodimentof the present invention, and (5-2-1) to (5-2-9) correspond to thereference numerals 1 to 9 in FIG. 18.

(5-2-1) The handover starts in response to the degradation of quality ofa signal the mobile unit 4 receives. The handover is conducted accordingto a decision in the upper node 1 made on the basis of a request fromthe mobile unit 4 or a radio situation report from the mobile unit 4.

(5-2-2) The upper node 1 makes a request to the handover addressed node3 for securing a resource accommodating the mobile unit 4 which carriesout the handover. In accordance with this request, the handoveraddressed node 3 secures the resource. In the case of a first messagetransmission/reception between the upper node 1 and the handoveraddressed node 3, the handover addressed node 3 newly activates a sharedchannel and activates a shared transport channel for the preparation ofthe handover and further transmits a handover preparation completion tothe upper node 1. If there is a channel already activated, it adds auser.

(5-2-3) The upper node 1 permits the handover addressing node 2 toimplement the handover.

(5-2-4) The upper node 1 transmits a handover instruction to the mobileunit 4. The mobile unit 4 secures the handover addressed node 3 and acommunication channel in accordance with this instruction.

(5-2-5) A bearer channel is set to transfer the data, left in thehandover addressing node 2, to the handover addressed node 3. Thisbearer channel can be set to make a direct connection between thehandover addressing node 2 and the handover addressed node 3 or it canalso be set to pass through the upper node 1.

(5-2-6) The upper node 1 makes a request for the transfer of a residualpacket to the handover addressing node 2.

(5-2-7) The handover addressing node 2 distributively transfers aresidual packet by a small volume to the handover addressed node 3. Thehandover addressed node 3 transmits the transferred residual packet anda new packet to the mobile unit 4 in the order of arrival.

(5-2-8) When the transfer of the residual packet reaches completion, thehandover addressing node 2 releases the resource secured by the mobileunit 4 which has carried out the handover.

(5-2-9) The upper node 1 releases the bearer channel set for theresidual packet transfer.

Thus, the residual packet is transferred in the intervals of thetransmission of a new packet, which enables efficient transfer.

(5-3) Change of Transmission Interval/Information Volume, Addition ofTransport Channel and Change of Subchannel Structure

FIG. 19 shows an example of a sequence for explaining a method for achange of transmission interval/information volume, an addition oftransport channel and a change of subchannel structure according to thefirst embodiment of the present invention, and (5-3-1) to (5-3-10)correspond to the reference numerals 1 to 10 in FIG. 19, respectively.

(5-3-1) The handover starts in response to the degradation of quality ofa signal the mobile unit 4 receives. The handover is conducted accordingto a decision in the upper node 1 made on the basis of a request fromthe mobile unit 4 or a radio situation report from the mobile unit 4.

(5-3-2) The upper node 1 makes a request to the handover addressed node3 for securing a resource accommodating the mobile unit 4 which carriesout the handover. In accordance with this request, the handoveraddressed node 3 secures the resource. In the case of a first messagetransmission/reception between the upper node 1 and the handoveraddressed node 3, the handover addressed node 3 newly activates a sharedchannel and activates a shared transport channel for the preparation ofthe handover and further transmits a handover preparation completion tothe upper node 1. If there is a channel already activated, it adds auser.

(5-3-3) The upper node 1 permits the handover addressing node 2 toimplement the handover.

(5-3-4) The upper node 1 transmits a handover instruction to the mobileunit 4. The mobile unit 4 secures the handover addressed node 3 and acommunication channel in accordance with this instruction.

(5-3-5) A bearer channel is set to transfer the data, left in thehandover addressing node 2, to the handover addressed node 3. Thisbearer channel can be set to make a direct connection between thehandover addressing node 2 and the handover addressed node 3 or it canalso be set to pass through the upper node 1.

(5-3-6) After the setting of the bearer channel for transfer, the uppernode 1 makes a request to the handover addressed node 3 for a change ofa transport channel such as an addition of a transfer transport channel,a change of transport channel transmission interval or an increase intransport channel transmission information volume so as to enableconcurrent transmission of transfer data and new packet. The handoveraddressed node 3 changes the transport channel in accordance with therequest from the upper node 1.

(5-3-7) The upper node 1 makes a request to the handover addressing node2 for transferring a residual packet. Upon receipt of the request, thehandover addressing node 2 starts to transmit the residual packet to thehandover addressed node 3.

(5-3-8) After the completion of transfer of the residual packet, thehandover addressing node 2 notifies the transfer completion to the uppernode 1. Upon receipt of the transfer completion notification, the uppernode 1 again transmits a transport channel change request to thehandover addressed node 3 to return the transport channel, added orchanged before the transfer, to the initial state before the change. Thehandover addressed node 3 returns the transport channel setting to thestate before the handover in accordance with the request from the uppernode 1.

(5-3-9) When the transfer of the residual packet reaches completion, thehandover addressing node 2 releases the resource secured by the mobileunit 4 which has carried out the handover.

(5-3-10) The upper node 1 releases the bearer channel set for theresidual packet transfer.

This enables maintaining the number of users to be accommodated whilesecuring the wide bandwidth, sharing a line with high efficiency at thesoft handover, avoiding the data residual even in the case of theemployment of variable communication rate, and preventing an increase inretransmission.

(B) Description of Second Embodiment of the Present Invention

Because of the use of wire transmission line when the handoveraddressing node 2 transmits a residual packet(s) to the handoveraddressed node 3, a signal loss or signal error seldom occurs. For thisreason, in the pattern A and the pattern B, a residual packet istransferred in a state where an overhead for assuring the integrity ofdata communication in a retransmission protocol or the like is notaffixed thereto.

On the other hand, in the pattern C and the pattern D which will bedescribed in the second embodiment, when a residual packet istransferred from the handover addressing node 2 to the handoveraddressed node 3, an overhead is affixed thereto and encapsulated. Thisassures the integrity of data communication from the handover addressingnode 2 to the handover addressed node 3 and assures the integrity ofdata communication from the handover addressing node 2 to the mobileunit 4.

A W-CDMA system according to the second embodiment is the same as theW-CDMA system 50.

(6) Description of Encapsulation of Transfer Data According to theSecond Embodiment

An object of the encapsulation is a residual packet frame to betransmitted from the handover addressing node 2 when the handoveraddressing node 2 transmits buffered data to the handover addressed node3. Employed is a method (tunneling method) in which the handoveraddressing node 2 does not carry out the disassembling and assembling ona frame header of a residual packet while the handover addressed node 3encapsulates the residual packet on the basis of an instruction from theupper node 1 or identification information included in the receivedresidual packet. Moreover, when all the residual packets buffered in thehandover addressing node 2 are transmitted to the mobile unit 4 and theresidual packet to be transmitted to the mobile unit 4 disappears, thehandover addressed node 23 terminates the encapsulation processing.

This encapsulation assures the integrity of data communication andenables high-speed processing.

For the encapsulation, the retransmission protocol used when thehandover addressing node 2 has made the transmission/reception withrespect to the mobile unit 4 before the handover is made to be used atthe data transfer among the handover addressing node 2, the handoveraddressed node 3 and the mobile unit 4.

The retransmission protocol used at the transmission/reception betweenthe handover addressed node 3 and the mobile unit 4 also exists in thedata communication between the handover addressed node 3 and the mobileunit 4. Therefore, two types of protocol headers of a protocol header tobe affixed in the handover addressing node 2 and a protocol header to beaffixed in the handover addressed node 3 are affixed to the sametransfer data.

(7) About Method of Affixing Two types of Headers

Methods for the transmission to the mobile unit 4 in a state where twotypes of headers are affixed to transfer data are roughly classifiedinto two types of methods (M1) and (M2).

-   -   (M1) A protocol header of the handover addressing node 2 and        user data transferred are encapsulated as one, and a protocol        header of the handover addressed node 3 is further affixed to        this encapsulated data.    -   (M2) When receiving the transfer data, the handover addressed        node 3 removes the protocol header affixed in the handover        addressing node 2 and reaffixes a protocol header, given by the        handover addressed node 3, to the transfer data.

A detailed description will be given of the above-mentioned two types ofmethods, and a description will be given of a sequence of a controlsignal and user data with respect to each node.

(7-1) Mode of Encapsulation

FIGS. 20(a), 20(b) to 24 are illustrations for explaining a packettransferring method according to the second embodiment of the presentinvention. In these illustrations, the parts which are the same as thosementioned above have the same or similar functions. In FIG. 20, ARQ-Hrepresents an ARQ header and, in the case of HS-DSCH, ARQ-H signifies a“header” of “H-ARQ”.

When the mobile unit 4 shown in FIG. 20(a) starts the handover, thehandover addressing node 2 detects the degradation of quality. Thehandover addressed node 3 affixes a header for H-ARQ (expressed asARQ-H) to user data from the upper node 1 with this detection as aturning-point (see FIG. 20(b)). Moreover, the upper node 1 detects thedegradation of quality and notifies the turning-point of the headeraffixation to the handover addressing node 2.

Furthermore, the handover addressing node 2 shown in FIG. 21 transmits asuspend request to the upper node 1 to suspend a new packet transmissionfor the residual packet transfer.

The handover addressing node 2 shown in FIG. 22(a) transfers a residualpacket through the upper node 1 to the handover addressed node 3, andthe handover addressed node 3 transmits this residual packet to themobile unit 4. At this time, the handover addressed node 3 furtheraffixes a header for H-ARQ to a packet with a header from the handoveraddressing node 2 (see FIG. 22(b)).

After the completion of the residual packet transfer, the handoveraddressing node 2 shown in FIG. 23 transmits a resume request to theupper node 1 for resuming new packet transmission.

In addition, the upper node 1 shown in FIG. 24(a) transmits a new packetto the handover addressed node 3, and the handover addressed node 3transmits the new packet to the mobile unit 4. At this time, thehandover addressed node 3 affixes a header for H-ARQ to the new packet(see FIG. 24 (b)).

Therefore, for the transfer/transmission, the handover addressing node 2encapsulates the residual packet according to an instruction from theupper node 1 or the discrimination of the received frame (firstencapsulation), and the handover node 3 encapsulates the residual packet(second encapsulation) and transmits the residual packet to the mobileunit 4.

Thus, the protocol header of the handover addressing node 2 and thetransferred user data are encapsulated into one and, in the handoveraddressed 3, the protocol header of the handover addressed node 3 isseparately affixed to this encapsulated data.

In the following description, the affixation of the protocol header,given in the handover addressing node 2, to the protocol header given inthe handover addressed node 3 is referred to as “share-ride”.

(7-2) Description of Share-Ride

In the case of the implementation of the share-ride, for thetransfer/transmission, discrimination information (information element)for the discrimination between an encapsulated packet and a normalpacket is inserted into a frame to be transmitted from the handoveraddressed node 3 to the mobile unit 4. That is, the discriminationinformation is inserted into the packet so that the ARQ of the mobileunit 4 can normally monitor two types of ARQs. As this insertion method,the following four patterns are employable.

(7-2-1) A pattern in which an area for indicating the share-ride isprovided in a packet and transfer data and a new packet are identical inheader and data length to each other.

FIGS. 25 (a) and 25 (b) are illustrations for explaining a first frameformat according to the second embodiment of the present invention. Theframe shown in FIG. 25(a) is made in a manner such that the handoveraddressed node 3 encapsulates transfer data from the handover addressingnode 2 and has three types of areas of a header given by the hand-overaddressed node 3, a header given by the handover addressing node 2 anduser data. The header given by the handover addressed node 3 includes asequence number (SN) indicative of an identification number affixed toeach data or each radio frame and identification information indicativeof whether the share-ride is implemented or not (whether a protocolheader is again affixed next).

The frame shown in FIG. 25(b) is made by encapsulating new data from theupper node 1. Although the share-ride is not implemented with respect tothis new packet, the handover addressed node 3 affixes, as a normalnon-used area, an area having a size needed for the insertion of theprotocol header of the handover addressing node 2 to the new packet sothat a data length of the new packet including a header portion and adata portion becomes equal to a data length of a transfer packet.

Therefore, for the transfer/transmission, a header area for a residualpacket is always secured in a frame to be transmitted from the handoveraddressed node 3 to the mobile unit 4. This eliminates the need for themobile unit 4 to make the discrimination between the encapsulated dataand the normal non-encapsulated information.

In addition, the handover addressed node 3 can also transmit aretransmission request due to conversion and a retransmission protocolor a response signal such as reception completion to the handoveraddressing node 2 by storing the handover addressing node 2 which hastransmitted a sequence number.

Still additionally, the mobile unit 4 recognizes the presence or absenceof a next header on the basis of this discrimination information and, ifthe next header exists (receiving an indication on the affixation of thenext header), reads out the next protocol header to acquire theshare-ride protocol information. On the other hand, if there is no nextheader (no indication on the affixation of the next header), the mobileunit 4 handles the area for the next protocol header as an invalid area,and it does not the contents thereof.

Thus, the handover addressed node 3 can recognize the presence orabsence of the next header as a portion of a protocol header. Moreover,the transfer data and the new packet are set at the same header and datalength and, hence, the header recognition processing procedure issimplified in the mobile unit 4.

(7-2-2) A pattern in which there is an area for indication on share-rideand transfer data and a new packet are different in header length fromeach other.

FIGS. 26(a) and 26(b) are illustrations for explaining a second frameformat according to the second embodiment of the present invention. Theframe shown in FIG. 26(a) is a frame which is transferred from ahandover addressing node and to which an ARQ header is affixed by thehandover addressed node 3. The ARQ header affixed in the handoveraddressed node 3 has an area indicative of the presence of a next headerarea. Accordingly, the handover addressed node 3 puts, in a portion ofthe header, identification information indicative of whether or not theshare-ride is conducted as a portion of the protocol header, that is,whether the protocol header is reaffixed next. This achieves theshare-ride of the protocol header affixed in the handover addressingnode 2 on the protocol header affixed in the handover addressed node 3.

On the other hand, since the protocol header of the handover addressingnode 2 is not affixed to a new packet (see FIG. 26(b)) which is notinvolved in the share-ride, the data length of the transfer data and thedata length of the new packet are different from each other. Therefore,each of the transmission side handover addressed node 3 and thereception side mobile unit 4 is equipped with two or more types of means(not shown) for identifying the data length.

(7-2-3) A pattern in which there is an area for indicating theshare-ride and the transfer data and the new packet are different indata length and header length from each other.

FIGS. 27 (a) and 27 (b) are illustrations for explaining a third frameformat according to the second embodiment of the present invention. Thehandover addressed node 3 places, as a portion of the protocol headershown in FIG. 27(a), identification information indicative of whether ornot the share-ride is conducted, that is, whether the protocol header isreaffixed next.

Moreover, since the protocol header of the handover addressing node 2 isnot affixed to a new packet (see FIG. 27 (b)) which is not involved inthe share-ride, the handover addressed node 3 changes the length of thedata portion to compensate for the difference in header length andcombines both the data portion and the header portion so that thetransmission data length becomes equal to that of the transfer data.Therefore, when the identification information indicates the affixationof the next header, the reception side mobile unit 4 again reads out theprotocol header to acquire the information on the share-ride protocol.Moreover, if there is no indication thereon, the mobile unit 4 conductsthe processing as the user data still continues.

(7-2-4) Header Compression

FIGS. 28 (a) and 28 (b) are illustrations for explaining a fourth frameformat according to the second embodiment of the present invention. Inthe frame shown in FIG. 28(a), identification information indicative ofthe “existence of header compression” is affixed, and transfer data anda new packet are set to be equal in header length to each other and setto be equal in data length to each other. Each of the handoveraddressing node 2 and the handover addressed node 3 compresses theprotocol header to shorten the header length and compensates for anincrease in transmission data length due to the share-ride of theprotocol header so that the transmission data length becomes equal tothat of the new packet.

Therefore, through the identification information included as a portionof the protocol header, the mobile unit 4 can recognize whether theheader compression is conducted or not. When the identificationinformation indicates the header compression, the mobile unit 4separates the read protocol header into the share-riding protocol headerand the share-ridden protocol header.

On the other hand, for example, like the frame as shown in FIG. 28(b),if there is no indication on the share-ride, the mobile unit 4 reads theheader and the data intact.

(7-3) Description of Operation When Encapsulated

The residual data encapsulated is transferred with this arrangement.

FIG. 29 shows an example of a sequence for explaining a residual packettransferring method based on encapsulation according to the secondembodiment of the present invention. In FIG. 29, “ARQ” expressed in eachof the mobile unit (UE) 4, a handover addressing node and a handoveraddressed node denotes an ARQ control unit 4 d (see FIG. 5), an ARQcontrol unit 2 d (see FIG. 3) and an ARQ control unit 3 d (see FIG. 4),and this also applies to the other drawings. The parts other than theseshave the same or similar functions as or to those of the above-mentionedparts. Moreover, (7-3-1) to (7-3-11) correspond to the referencenumerals 1 to 11 in FIG. 29.

(7-3-1) The handover starts in response to the degradation of quality ofa signal the mobile unit 4 receives. The handover is conducted accordingto a decision in the upper node 1 made on the basis of a request fromthe mobile unit 4 or a radio situation report from the mobile unit 4.

(7-3-2) The upper node 1 makes a request to the handover addressed node3 for securing a resource accommodating the mobile unit 4 which carriesout the handover. In accordance with this request, the handoveraddressed node 3 secures the resource. In the case of a first messagetransmission/reception between the upper node 1 and the handoveraddressed node 3, the handover addressed node 3 newly activates a sharedchannel. If there is a channel already activated, the handover addressednode 3 adds a user.

(7-3-3) The upper node 1 permits the handover addressing node 2 toimplement the handover. Upon receipt of the permission, the handoveraddressing node 2 transmits a suspend request to the upper node 1 forsuspending the new packet transmission. Incidentally, in this sequence,in place of a suspend request being transmitted from the handoveraddressing node 2, it is also appropriate that the upper node 1 itselfsuspends the new packet transmission.

(7-3-4) The upper node 1 transmits a handover instruction to the mobileunit 4. The mobile unit 4 secures the handover addressed node 3 and acommunication channel in accordance with this instruction.

(7-3-5) In this handover, the mobile unit 4 activates, in addition to aretransmission protocol entity activated for the handover addressingnode 2 (provided in opposed relation to the handover addressing node 2),a retransmission protocol entity for the handover addressed node 3.

(7-3-6) A bearer channel for transfer is set between the handoveraddressing node 2 and the upper node 1, and a path is set to transferthe data, left in the handover addressing node 2, to the handoveraddressed node 3 by the upper node 1. This bearer channel can also beset to make a direct connection between the handover addressing node 2and the handover addressed node 3.

(7-3-7) The upper node 1 makes a request for the transfer of a residualpacket to the handover addressing node 2. The handover addressing node 2transfers the residual packet to the handover addressed node 3 throughthe bearer channel set in (7-3-6).

The handover addressed node 3 receives the residual packet from thehandover addressing node 2 and transmits it to the mobile unit 4. Atthis time, continuing before the handover, the handover addressing node2 affixes the protocol header to the transfer data and transfers it. Thehandover addressed node 3 conducts the share-ride of its own protocolheader on this transfer data and transfers it to the mobile unit 4.

(7-3-8) When the transfer of the residual packet reaches completion, thehandover addressing node 2 releases the resource secured by the mobileunit 4 which has carried out the handover and outputs a resume requestto the upper node 1 for making a request for the resumption oftransmission of the new packet. Incidentally, in the sequence, althoughthe handover addressing node 2 outputs the resume request, it is alsoappropriate that the upper node 1 itself conducts it.

(7-3-9) When receiving the resume request, the upper node 1 releases thebearer channel set for the residual packet transfer.

(7-3-10) The upper node 1 gives an instruction to the mobile unit 4 forreleasing the retransmission protocol entity on the handover addressingnode 2. The mobile unit 4 releases the retransmission entity on thehandover addressing node 2 in accordance with this instruction.

(7-3-11) The transmission of a new packet is resumed.

Thus, the protocol header of the handover addressing node 2 and thetransferred data are encapsulated and the protocol header of thehandover addressed node 3 is affixed to this encapsulated data.

This enables assuring the integrity of data communication from thehandover addressing node 2 to the handover addressed node 3 and furtherassuring the integrity of data communication from the handoveraddressing node 2 to the mobile unit 4.

(7-4) About Method of Re-Affixing Protocol Header

Upon receipt of transfer data, the handover addressed node 3 removes theprotocol header affixed in the handover addressing node 2 and newlyaffixes a protocol header thereto. In the (M1) method, the protocolheaders affixed by the handover addressing node 2 and the handoveraddressed node 3 are used, while in the (M2) method, the protocol headeris reaffixed without affixing the two types of protocol headers. Thisretransmission control can employ the following two patterns, whichenables the retransmission control similar to (M1).

(7-4-1) A method of setting an association table between a headeraffixed in the handover addressing node 2 and a header affixed in thehandover addressed node 3.

FIG. 30 is an illustration for explaining a method of affixing headerinformation to transfer data through the use of an association tableaccording to the second embodiment of the present invention. Thehandover addressed node 3 shown in FIG. 30 has an association tablebetween a header affixed in the handover addressing node 2 and a headeraffixed in the handover addressed node 3. For example, with respect toof a user A of the handover addressing node 2, ARQ information in thehandover addressing node 2, a user name and ARQ information (its own ARQinformation) in the handover addressed node 3 are associated with eachother and recorded in the association table 10. In this case, the ARQinformation in the handover addressing node 2 signifies, for example,SNR (Signal Noise Ratio) information given in the handover addressingnode 2 and included in the protocol header, or the like. Moreover, theARQ information in the handover addressed node 3 signifies protocolheader information given in the handover addressed node 3, or the like.

When these information are recorded in the association table 10 in astate associated with each other, the change in affixation from theprotocol header of the handover addressing node 2 to the protocol headerof the handover addressed node 3 becomes feasible. Thus, with respect tothe packet to be transmitted from the handover addressed node 3 to themobile unit 4, the retransmission protocol can be managed through theuse of one type of protocol header.

In FIG. 30, the parts marked with the same reference numerals as thoseused above have the same or similar functions, and the repeateddescription thereof will be omitted.

In this case, since the handover addressed node 3 receives new packetsfrom a plurality of users or packets are transferred thereto from aplurality of handover addressing nodes 2, the association table 10records information (for example, user identification information, lineidentification information, or the like) for identifying entities in thehandover addressing nodes 2, thus identifying a plurality of users and aplurality of handover addressing nodes 2.

As the processing in the handover addressed node 3, in a processingmethod in the case of the data transmission in the direction from thehandover addressing node 2 through the handover addressed node 3 to themobile unit 4, the handover addressed node 3 records a user name of datareceived from the handover addressing node 2 and the ARQ informationthereon. Subsequently, the line terminating unit 2 b (see FIG. 3) of thehandover addressed node 3 transmits the data excluding the ARQ header tothe ARQ control unit 3 d (see FIG. 3). Moreover, the own ARQ informationassigned by the ARQ control unit 3 d and the recorded ARQ information ofthe handover addressing node 2 are paired and written in the associationtable 10.

On the other hand, in the case of the directions from the mobile unit 4through the handover addressed node 3 to the handover addressing node 2,the receiving unit 2 a (see FIG. 3) of the handover addressed node 3receives ACK from the mobile unit 4 to the ARQ control unit 3 d of thehand-over addressed node 3. Subsequently, it retrieves the handoveraddressed node 3 (ARQ information), included in the ACK, from theassociation table 10 to extract the user name of the handover addressingnode 2 and the ARQ information of the handover addressing node 2.Moreover, it transmits the ACK, produced on the basis of the ARQinformation of the handover addressing node 2 extracted, to theextracted user (handover addressing node 2).

In addition, the handover addressed node 3 makes a comparison betweenits own entity information found on the basis of the acknowledge (ACK)and the non-acknowledge (NACK), received from the mobile unit 4, and theassociation table 10 and, through this comparison, the handoveraddressed node 3 identifies the handover addressing node 2 which hastransferred that data, and converts the ACK/NACK information fortransmitting the converted ACK/NACK information to the handoveraddressing node 2.

Thus, for the transfer/transmission, the handover addressed node 3carries out the transmission/reception on a frame with respect to themobile unit 4 on the basis of the association table 10, i.e., the headeraffixed in the handover addressing node 2 and the header affixed in thehandover addressed node 3.

(7-4-2) A method of terminating a header, affixed in the handoveraddressing node 2, in the handover addressed node 3.

FIG. 31 is an illustration for explaining a method of terminating aheader, affixed in the handover addressing node 2, in the handoveraddressed node 3. The handover addressed node 3 shown in FIG. 31 has atermination processing unit 11. This termination processing unit 11terminates the ARQ, affixed in the handover addressing node 2 andincluded in transfer data (transfer packet), and acquires only user dataand returns ACK to the handover addressing node 2.

In addition, a protocol header is affixed to a transfer packet in thehandover addressing node 2 and the transfer packet is transmitted to thehandover addressed node 3 and terminated in the termination processingunit 11 of the handover addressed node 3 and re-carried. The handoveraddressed node 3 confirms the transfer data received from the handoveraddressing node 2 and returns an acknowledge (ACK) signal to thathandover addressing node 2. The handover addressed node 3 removes theprotocol header, affixed in the handover addressing node 2, from thetransfer data, and affixes the protocol header of its own entity theretoand transmits it to the mobile unit 4.

In FIG. 31, the parts marked with the same reference numerals as thoseused above have the same or similar functions.

(7-5) Description of Operation for Removal of Header

FIG. 32 shows an example of a sequence for explaining a residual packettransferring method based on re-affixation of a protocol headeraccording to the second embodiment of the present invention, and (7-5-1)to (7-5-9) correspond to the reference numerals 1 to 9 in FIG. 32,respectively.

(7-5-1) The handover starts in response to the degradation of quality ofa signal the mobile unit 4 receives. The handover is conducted accordingto a decision in the upper node 1 made on the basis of a request fromthe mobile unit 4 or a radio situation report from the mobile unit 4.

(7-5-2) The upper node 1 makes a request to the handover addressed node3 for securing a resource accommodating the mobile unit 4 which carriesout the handover. In accordance with this request, the handoveraddressed node 3 secures the resource. In the case of a first messagetransmission/reception between the upper node 1 and the handoveraddressed node 3, the handover addressed node 3 newly activates a sharedchannel and activates a shared transport channel for the preparation ofthe handover, and transmits the handover preparation completion to theupper node 1. If there is a channel already activated, it adds a user.

(7-5-3) The upper node 1 permits the handover addressing node 2 toimplement the handover. Upon receipt of the permission, the handoveraddressing node 2 transmits a suspend request to the upper node 1 forsuspending the new packet transmission. Incidentally, in this sequence,in place of a suspend request being transmitted from the handoveraddressing node 2, it is also appropriate that the upper node 1 itselfconducts this.

(7-5-4) The upper node 1 transmits a handover instruction to the mobileunit 4. The mobile unit 4 secures the handover addressed node 3 and acommunication channel in accordance with this instruction.

(7-5-5) A bearer channel is set to transfer the data, left in thehandover addressing node 2, to the handover addressed node 3. Thisbearer channel can be set to make a direct connection between thehandover addressing node 2 and the handover addressed node 3, or it canalso be set by way of the upper node 1.

(7-5-6) The upper node 1 makes a request for the transfer of a residualpacket to the handover addressing node 2. The handover addressing node 2transfers the residual packet to the handover addressed node 3 throughthe bearer channel set in the previous paragraph. The handover addressednode 3 receives the residual packet from the handover addressing node 2and transmits it to the mobile unit 4. At this time, continuing beforethe handover, the handover addressing node 2 affixes the protocol headerto the transfer data and transfers it. The handover addressed node 3terminates the protocol header affixed in the handover addressing node 2and re-affixes it own protocol header and transmits it to the mobileunit 4.

(7-5-7) When the transfer of the residual packet reaches completion, thehandover addressing node 2 releases the resource secured by the mobileunit 4 which has carried out the handover and outputs a resume requestto the upper node 1 for making a request for the resumption oftransmission of the new packet. Incidentally, in the sequence, althoughthe handover addressing node 2 outputs the resume request, it is alsoappropriate that the upper node 1 itself conducts it.

(7-5-8) When receiving the resume request, the upper node 1 releases thebearer channel set for the residual packet transfer.

(7-5-9) The transmission of a new packet is resumed.

Thus, since the handover addressed node 3 re-affixes the protocolheader, it is possible to maintain the number of users to beaccommodated while securing the wide bandwidth, and to share the linewith high efficiency at the soft handover.

(8) Description of Pattern D

The pattern D is a method of transmitting a new packet even in themiddle of the transfer of a residual packet and encapsulating transferdata.

(8-1) In the handover addressed node 3, this pattern D is made so as totransmit the transfer data left in the handover addressing node 2 and anew packet transmitted from the upper node 1 to the mobile unit 4 whilecarrying out the arbitration therebetween. The arbitration method can bethe same as that described in the pattern B.

Moreover, although the encapsulation and re-affixation of the protocolheader affixed in the handover addressing node 2 are made at theresidual packet transfer, this method can be the same in contents asthat described in the pattern C.

FIGS. 33(a), 33(b) to 35(a), 35(b) are illustrations for explaininganother packet transferring method according to the second embodiment ofthe present invention. In these illustrations, the same parts as thosementioned above have the same or similar functions.

When the mobile unit 4 shown in FIG. 33(a) starts the handover, thehandover addressing node 2 detects the quality degradation. On the basisof this detection, the handover addressed node 3 affixes a header forH-ARQ to user data from the upper node 1 (see FIG. 33(b)). This headeraffixation is notified to the handover addressing node 2 when the uppernode 1 detects the quality degradation.

In addition, the handover addressing node 2 shown in FIG. 34(a)transfers a residual packet to the upper node 1, with the residualpacket and a new packet being transmitted from the upper node 1 to thehandover addressed node 3 while being arbitrated therebetween. Stilladditionally, the handover addressed node 3 transmits the residualpacket and the new packet to the mobile unit 4.

Moreover, to the user data shown in FIG. 34(b), H-ARQ is affixed when itis transferred from the handover addressing node 2 to the upper node 1.Still moreover, H-ARQ is further affixed thereto for the share-ride whenthe handover addressed node 3 transmits a packet, transferred from theupper node 1, to the mobile unit 4.

When the handover addressing node 2 shown in FIG. 35(a) completes thetransfer of the residual packet, the upper node 1 transmits a new packetto the handover addressed node 3. At this time, the handover addressednode 3 affixes a header for H-ARQ to the new packet shown in FIG. 35(b).

(8-2) Align

A description will be given of a length adjusting method of preventing aradio frame length to becomes long due to the share-ride in the case ofthe encapsulation. A share-ride header is an H-ARQ header inserted intoa transfer packet in the handover addressing node 2 and the handoveraddressed node 3, and the radio frame length can exceed a predeterminedformat length due to the addition of this share-ride header and others.

When this situation occurs, for aligning to the radio frame format, thehandover addressed node 3 adjusts the radio frame length to apredetermined format length through the use of shortening of theresidual packet side data length, data division or header compression.In this connection, it is preferable that the handover addressed node 3stores the base station which has transmitted the sequence number andcarries out the transmission/reception of a retransmission requestaccording to conversion and retransmission protocol or a response signalsuch as reception completion with respect to the handover addressingnode 2.

On the other hand, the handover addressed node 3 can notify thissituation to the upper node 1, and the upper node 1 can output aninstruction to each node for lengthening the radio frame format.

That is, for the transfer/transmission, the handover addressed node 3monitors the capacity of a share-ride frame including a protocol headeraffixed in the handover addressing node 2 and a protocol header affixedto a frame transmitted to the mobile unit 4 (monitor step) and, when thecapacity of the share-ride frame in the monitor step exceeds apredetermined value, the handover addressed node 3 aligns the share-rideframe by shortening the share-ride frame or by increasing the radioframe format (align step).

For example, the case in which the capacity of the share-ride frameexceeds a predetermined prescribed capacity corresponds to, in additionto the case (see FIGS. 13(a) and 13(b)) in which an excessive transferpacket or new packet is received when the information volume to betransmitted from the handover addressed node 3 to the mobile unit 4 isdecreased, a case (see FIGS. 25(a), 25(b) to FIGS. 28(a), 28(b)) inwhich the total length of the header portion and the data portionexceeds a prescribed length due to the share-ride, or other cases.

Moreover, when a situation exceeding the radio frame format occurs atthe share-ride, for the alignment, the handover addressed node 3shortens the packet length of the residual packet. Concretely, itcarries out the shortening of the data portion of the residual packet,the compression of the header portion and the division of the dataportion of the residual packet.

Still moreover, in place of the shortening of the transmission packetlength, it is also possible to increase the frame format in a radiozone. That is, for the alignment, the handover addressed node 3 can seta radio frame format with a capacity larger than the capacity of theshare-ride frame which exceeds the predetermined capacity. Concretely,when a situation exceeding the radio frame format occurs at theshare-ride, the handover addressed node 3 notifies this information tothe upper node 1 and receives an instruction from the upper node 1 tolengthen the radio frame format length so that the transmission is madein a state where the radio frame length coincides with the data lengthon the residual data side.

(8-3) Activation Time (Time of Activation)

After the completion of the handover, the mobile unit 4 receives theencapsulated data and the normal non-encapsulated data in a mixedcondition from the handover addressed node 3. Accordingly, the mobileunit 4 requires a segmentation for the discrimination between both thedata. For this reason, the handover addressing node 2 is made to notify,as activation time, the timings of the first and last segments of thedata transfer time period to the handover addressed node 3. That is, forthe transfer/transmission, the activation time recognizable by both thehandover addressed node 3 itself and the mobile unit 4 is used for theframe to be transmitted from the handover addressed node 3 to the mobileunit 4, thereby enabling the discrimination between the encapsulatedpacket and the normal packet.

In this case, when time is used as the activation time, the segmenttiming is expressed by a radio frame timing. Moreover, for example, themobile unit 4 makes a discrimination with reference to the leading bitof the radio frame such that the time zone before the leading bit istaken as the non-encapsulation and the time zone after it is taken asthe encapsulation.

In addition, in a case in which a sequence number is used as theactivation time, the segment timing is expressed as “a given number andnumbers subsequent thereto” of the user data. As the activation time,for example, if the sequence number is “10”, the mobile unit 4 makes adiscrimination such that the data with the sequence numbers “0” to “10”are not encapsulated while the data with the sequence numbers subsequentto “10” are encapsulated.

Incidentally, it is preferable that the upper node 1 determines theactivation time. Moreover, when determining this activation time, theupper node 1 notifies an instruction to both the handover addressed node3 and the mobile unit 4. These utilizes the activation time recognizedin common.

(8-4) Moreover, when the handover addressed node 3 confirms thetransmission/arrival with respect to the mobile unit 4 through the useof the sequence numbers, with respect to the data using a first H-ARQaffixed in the handover addressing node 2, the handover addressed node 3can also transmit a response signal on the retransmission or receptioncompletion. Thus, the handover addressing node 2 releases the buffer 2 gfor the data to be transmitted to the mobile unit 4. Following this, thehandover addressed node 3 transmits the data, transmitted from thehandover addressing node 2, through H-ARQ to the mobile unit 4.

Therefore, for the transfer/transmission, the handover addressed node 3converts the H-ARQ information, used between the handover addressingnode 2 and the mobile unit 4, into the H-ARQ information used betweenthe handover addressed node 3 and the mobile unit 4.

In addition, for the transfer/transmission, it is also possible that,with respect to the data using the first H-ARQ transmitted from thehandover addressing node 2, the handover addressed node 3 transmits aresponse signal on the retransmission or reception completion and thehandover addressing node 2 releases the buffer for holding a packet tothe mobile unit 4 (release step) and the handover addressed node 3transmits the data, transmitted from the handover addressing node 2,through a second H-ARQ to the mobile unit 4 (transmission step).

(9) Description of Operation of Pattern D

(9-1) A description will be given of an example of a sequence employingthe header share-ride based on encapsulation and the arbitration basedon a resource allocation request.

As the sequence example, a description will be given of a case ofemploying a protocol header share-ride method based on encapsulation andan arbitration method based on a resource allocation request and a caseof employing a protocol header re-affixation and an arbitration methodusing a resource allocation request. It is also possible to employ amethod using a different arbitration method and a method using protocolheader encapsulation or re-affixation method.

FIG. 36 shows an example of a sequence for explaining the pattern Daccording to the second embodiment of the present invention, and (9-1-1)to (9-1-11) correspond to the reference numerals 1 to 11 in FIG. 36,respectively.

(9-1-1) The handover starts in response to the degradation of quality ofa signal the mobile unit 4 receives. The handover is conducted accordingto a decision in the upper node 1 made on the basis of a request fromthe mobile unit 4 or a radio situation report from the mobile unit 4.

(9-1-2) The upper node 1 makes a request to the handover addressed node3 for securing a resource accommodating the mobile unit 4 which carriesout the handover. In accordance with this request, the handoveraddressed node 3 secures the resource. In the case of a first messagetransmission/reception between the upper node 1 and the handoveraddressed node 3, the handover addressed node 3 newly activates a sharedchannel and activates a shared transport channel for the preparation ofthe handover and transmits the handover preparation completion to theupper node 1. If there is a channel already activated, it adds a user.

(9-1-3) The upper node 1 permits the handover addressing node 2 toimplement the handover.

(9-1-4) The upper node 1 transmits a handover instruction to the mobileunit 4. The mobile unit 4 secures the handover addressed node 3 and acommunication channel in accordance with this instruction.

(9-1-5) In this handover, the mobile unit 4 activates, in addition to aretransmission protocol entity for the handover addressing node 2, aretransmission protocol entity for the handover addressed node 3.

(9-1-6) A bearer channel is set to transfer the data, left in thehandover addressing node 2, to the handover addressed node 3. Thisbearer channel can be set to make a direct connection between thehandover addressing node 2 and the handover addressed node 3, or it canalso be set by ways of the upper node 1.

(9-1-7) The upper node 1 makes a request for the transfer of a residualpacket to the handover addressing node 2.

(9-1-8) The handover addressing node 2 transmits a request to thehandover addressed node 3 for allocating resources needed fortransmitting the residual packet. After the reception of this request,the handover addressed node 3 secures a resource corresponding to therequest and notifies the resource securement to the handover addressingnode 2. Upon receipt of the notification on the resource securement, thehandover addressing node 2 starts to transfer the residual packet.

The handover addressed node 3 transmits the transferred residual packetand a new packet to the mobile unit 4 according to the resourceassigned. At this time, continuing before the handover, the handoveraddressing node 2 affixes the protocol header to the transfer data andtransfers it. The handover addressed node 3 conducts the share-ride ofits own protocol header on this transfer data and transfers it to themobile unit 4.

(9-1-9) When the transfer of the residual packet reaches completion, thehandover addressing node 2 releases the resource secured by the mobileunit 4 which has carried out the handover.

(9-1-10) The upper node 1 releases the bearer channel set for theresidual packet transfer.

(9-1-11) The upper node 1 gives an instruction to the mobile unit 4 forreleasing the retransmission protocol entity confronting the handoveraddressing node 2. The mobile unit 4 releases the retransmissionprotocol entity for the handover addressing node 2 in accordance withthis instruction.

Thus, the arbitration becomes feasible through the use of the headershare-ride based on the encapsulation and the resource allocationrequest, which assures the integrity of the data communication.

(9-2) Description of Operation in the Case of Employment of HeaderRe-Affixation and Resource Allocation Request

FIG. 37 shows an example of a sequence for explaining an arbitrationmethod using header re-affixation and resource allocation requestaccording to the second embodiment of the present invention, and (9-2-1)to (9-2-9) correspond to the reference numerals 1 to 9 in FIG. 37,respectively.

(9-2-1) The handover starts in response to the degradation of quality ofa signal the mobile unit 4 receives. The handover is conducted accordingto a decision in the upper node 1 made on the basis of a request fromthe mobile unit 4 or a radio situation report from the mobile unit 4.

(9-2-2) The upper node 1 makes a request to the handover addressed node3 for securing a resource accommodating the mobile unit 4 which carriesout the handover. In accordance with this request, the handoveraddressed node 3 secures the resource. In the case of a first messagetransmission/reception between the upper node 1 and the handoveraddressed node 3, the handover addressed node 3 newly activates a sharedchannel and activates a shared transport channel for the preparation ofthe handover and transmits the handover preparation completion to theupper node 1. If there is a channel already activated, it adds a user.

(9-2-3) The upper node 1 permits the handover addressing node 2 toimplement the handover.

(9-2-4) The upper node 1 transmits a handover instruction to the mobileunit 4. The mobile unit 4 secures the handover addressed node 3 and acommunication channel in accordance with this instruction.

(9-2-5) A bearer channel is set to transfer the data, left in thehandover addressing node 2, to the handover addressed node 3. Thisbearer channel can be set to make a direct connection between thehandover addressing node 2 and the handover addressed node 3, or it canalso be set by ways of the upper node 1.

(9-2-6) The upper node 1 makes a request for the transfer of a residualpacket to the handover addressing node 2.

(9-2-7) The handover addressing node 2 transmits a request to thehandover addressed node 3 for allocating resources needed fortransmitting the residual packet. After the reception of this request,the handover addressed node 3 secures a resource corresponding to therequest and notifies the resource securement to the handover addressingnode 2. Upon receipt of the notification on the resource securement, thehandover addressing node 2 starts to transfer the residual packet. Thehandover addressed node 3 transmits the transferred residual packet anda new packet to the mobile unit 4 according to the resource assigned.

At this time, continuing before the handover, the handover addressingnode 2 affixes the protocol header to the transfer data and transfersit. The handover addressed node 3 terminates the protocol header affixedin the handover addressing node 2 and re-affixes its own protocol headerthereto and transfers it to the mobile unit 4.

(9-2-8) When the transfer of the residual packet reaches completion, thehandover addressing node 2 releases the resource secured by the mobileunit 4 which has carried out the handover.

(9-2-9) The upper node 1 releases the bearer channel set for theresidual packet transfer.

Thus, the arbitration using the header re-affixation and the resourceallocation request is employed, which enables transferring the datacompletely.

The present invention is not limited to the above-described embodiments,and it covers all changes of the embodiments of the invention hereinwhich do not constitute departures from the spirit and scope of theinvention.

In FIG. 1, in a case in which, for example, the mobile unit 4 shiftsfrom the base station 3-0 to the base station 3-3, the handover isfeasible by conducting the switching from the HS-DSCH for controllingthe base station 3-0 to the HS-DSCH for controlling the base station3-3. Also in this case, the base station 3-0 can transmit/receive amessage, similar to that mentioned above, to/from the base station 3-3,the RNC 2-0 or the exchanger 1 and transfer the residual data, left inthe base station 3-0 itself, to the base station 3-3. Also in the caseof the employment of DSCH, the switching between the DSCHs is feasible.

(C) Others

(1) In the aforesaid transfer/transmission step, it is also possiblethat at least one of the handover addressing node 2 and the upper node 1secures a resource for holding a residual packet and conducts thearbitration to transmit a new packet to the handover addressed node 3.

(2) It is also appropriate that the aforesaid transfer/transmission stepincludes a measurement step in which at least one node of the handoveraddressing node 2 and the upper node 1 measures the capacity of aresource provided in the handover addressed node 3 for holding aresidual packet and an arbitration step in which the handover addressingnode 2 transfers a transferable portion of a residual packet for thearbitration on the basis of the capacity of the resource measured in themeasurement step.

(3) It is also appropriate that, in the aforesaid transfer/transmissionstep, anyone of the handover addressed node 3, the handover addressingnode 2 and the upper node 1 adjusts the number of divisions of aresidual packet for the arbitration on the basis of the capacity of aresource for holding a new packet.

(4) It is also appropriate that the aforesaid transfer/transmission stepincludes a division step in which the handover addressing node 2 dividesa residual packet into a plurality of packets having a data volumecorresponding to a communication rate in a radio zone, a divisiontransmission step in which the handover addressing node 2 transmits theplurality of divided packets in the division step to the handoveraddressed node 3, and an order-of-arrival transmission step in which thehandover addressed node 3 transmits a plurality of packets including theplurality of divided packets transmitted in the division transmissionstep and a plurality of new packets in a mixed condition to the mobileunit 4 on the basis of the order of reception.

(5) It is also appropriate that, in the aforesaid transfer/transmissionstep, the handover addressed node 3 is made to change a transmissioninterval in a radio zone.

(6) It is also appropriate that, in the aforesaid division transmissionstep, the handover addressed node 3 is made to change a radiotransmission interval when transferring a packet.

(7) It is also appropriate that, in the aforesaid division transmissionstep, the handover addressing node 2 makes the transmission whilechanging a data volume in a unit transmission interval.

(8) It is also appropriate that, in the aforesaid transfer/transmissionstep, the handover addressed node 3 is made to change a frame format ina radio zone.

(9) It is also appropriate that, in the aforesaid transfer/transmissionstep, the handover addressed node 3 is made to terminates information onretransmission control affixed in the handover addressing node 2 andincluded in a transfer packet and acquires user data for retransmissioncontrol.

(10) It is also appropriate that, in the aforesaid transfer/transmissionstep, the handover addressed node 3 is made to always secure a headerarea for a residual packet in a frame to be transmitted to the mobileunit 4.

(11) It is also appropriate that the aforesaid transfer/transmissionstep includes a monitor step in which the handover addressed node 3monitors a capacity of a share-ride frame including a protocol headeraffixed in the handover addressing node 2 and a protocol header affixedto a frame to be transmitted to the mobile unit 4 and an align step inwhich, when the capacity of the share-ride frame in the monitor stepexceeds a predetermined value, the handover addressed node 3 aligns theshare-ride frame through the use of one of shortening of the share-rideframe and increase of a radio frame format.

(12) It is also appropriate that, in the aforesaid align step, thehandover addressed node 3 shortens a packet length of a residual packet.

(13) It is also appropriate that, in the aforesaid align step, thehandover addressed node 3 sets a radio frame format having a capacitylarger than a capacity of the share-ride frame exceeding a predeterminedcapacity.

(14) It is also appropriate that, in the aforesaid transfer/transmissionstep, the handover addressed node 3 is made to employ an activationtime, recognizable by both the handover addressed node 3 itself and themobile unit 4, in a frame to be transmitted to the mobile unit 4 formaking a discrimination between an encapsulated packet and a normalpacket.

(15) It is also appropriate that, in the aforesaid transfer/transmissionstep, the handover addressed node 3 is made to store a lower node, whichhas transmitted a sequence number, and transmit a retransmission requestaccording to conversion/retransmission protocol or a response signalsuch as reception completion to the handover addressing node 2.

(16) It is also appropriate that the aforesaid transfer/transmissionstep includes a release step in which the handover addressed node 3transmits a response signal on retransmission or reception completionwith respect to data under first hybrid retransmission controltransmitted from the handover addressing node 2 so that handoveraddressing node 2 releases a buffer holding a packet addressed to themobile unit 4, and a transmission step of transmitting data transmittedfrom the handover addressing node 2 to the mobile unit 4 through the useof second hybrid retransmission control.

(17) It is also appropriate that the aforesaid second transmitting unitaffixes a retransmission control header on the basis of identificationinformation indicative of the presence or absence of a share-ride frameincluding a first header affixed to a radio frame to be transmitted tothe mobile unit 4 and a second header affixed in the handover addressingnode 2 and a packet length.

INDUSTRIAL APPLICABILITY

As described above, in a W-CDMA system, the present invention eliminatesthe need for transmitting the same signal through the use of a pluralityof channels from a base station to a mobile unit at handover, thusincreasing the number of users and improving the communication quality,and achieving effective utilization of transmission lines and radioresources.

In addition, the loss of user data is preventable, and the qualities ofvarious types of services such as the stability of communication rateand real-time performance are improvable. Still additionally, the costperformance in the W-CDMA is improvable.

1. A packet transferring/transmitting method for use in a mobilecommunication system including an upper node for transmitting aplurality of packets addressed to a mobile unit, a handover addressingnode for transmitting a plurality of packets addressed to said mobileunit and a handover addressed node for transmitting a plurality ofpackets addressed to said mobile unit, said method comprising: adetermination step in which said upper node determines implementation ofhandover; and a transfer/transmission step in which said handoveraddressing node transfers, of said plurality of packets, anon-transmitted residual packet to said handover addressed node and saidupper node transmits a packet to said handover addressed node.
 2. Thepacket transferring/transmitting method according to claim 1, wherein,in said transfer/transmission step, said handover addressing node orsaid upper node itself suspends the transmission of a packet from saidupper node at the transfer of said residual packet.
 3. The packettransferring/transmitting method according to claim 1, wherein saidtransfer/transmission step includes a channel setting step in which saidupper node carries out one of allocation of a separate transfer channeland securement of an added channel between said handover addressed nodeand said handover addressing node on the basis of a packet volume in aradio zone; a scheduling step in which said handover addressed nodecarries out scheduling on packet transmission through the use of saidseparate transfer channel or said added channel secured in said channelsetting step and the new channel; and a scheduling transmission step inwhich said handover addressed node transmits said packet and saidresidual packet to said mobile unit on the basis of the scheduling insaid scheduling step.
 4. The packet transferring/transmitting methodaccording to claim 1, wherein, in said transfer/transmission step, saidhandover addressing node first-encapsulates said residual packetaccording to an instruction from said upper node or identification on areceived frame, and said handover addressed node second-encapsulatessaid residual packet and transmits said residual packet to said mobileunit.
 5. The packet transferring/transmitting method according to claim1, wherein, in said transfer/transmission step, said handover addressednode conducts transmission/reception of a frame with respect to saidmobile unit on the basis of an association table between a headeraffixed in said handover addressing node and a header affixed in saidhandover addressed node.
 6. The packet transferring/transmitting methodaccording to claim 4, wherein, in said transfer/transmission step, saidhandover addressed node inserts discrimination information for adiscrimination between an encapsulated packet and a normal packet into aframe to be transmitted to said mobile unit.
 7. The packettransferring/transmitting method according to claim 4, wherein, in saidtransfer/transmission step, said handover addressed node converts firsthybrid retransmission control information used between said handoveraddressing node and said mobile unit into second hybrid retransmissioncontrol information used between said handover addressed node and saidmobile unit.
 8. A mobile communication system equipped with an uppernode for transmitting a plurality of packets addressed to a mobile unit,said handover addressing node for transmitting a plurality of packetsaddressed to said mobile unit and said handover addressed node formaking transmission/reception of a packet with respect to said mobileunit after the handover, wherein said handover addressing nodecomprises: a first line receiving unit for receiving a packet from saidupper node; a buffer for holding said packet received in said first linereceiving unit; a first retransmission control unit for carrying outretransmission control on a packet volume to be transferred, on thebasis of a resource capacity of said handover addressed node included insaid packet received in said first line receiving unit and a residualvolume of said packet held in said buffer; and a first line transmittingunit for, on the basis of said packet volume retransmission-controlledin said first retransmission control unit, transmitting said packet heldin said buffer to said handover addressed node without interposing saidupper node therebetween or by way of said upper node.
 9. A mobilecommunication system equipped with an upper node for transmitting aplurality of packets addressed to a mobile unit, said handoveraddressing node for transmitting a plurality of packets addressed tosaid mobile unit and said handover addressed node for makingtransmission/reception of a packet with respect to said mobile unitafter the handover, wherein said handover addressed node comprises: asecond line receiving unit for receiving a plurality of packets fromsaid upper node and said handover addressing node; a secondretransmission control unit for carrying out retransmission control onsaid packets received in said second line receiving unit; and a secondtransmitting unit for affixing a retransmission control headerundergoing the retransmission control in said second retransmissioncontrol unit to said plurality of packets received in said second linereceiving unit to transmit a radio frame with said header to said mobileunit.
 10. A mobile communication system having a function to switch atransmission path, from an upper apparatus to a mobile unit, fromtransmission by a handover addressing node to transmission by a handoveraddressed node, wherein said handover addressing node comprisestransferring means for transferring data, addressed to said mobile unitand left in said handover addressing node to said handover addressednode at the switching, and said handover addressed node comprisestransmitting means for transmitting, to said mobile unit, said datatransferred and received therefrom and said data from said upperapparatus.
 11. The mobile communication system according to claim 10,wherein data transmission from said upper apparatus to said handoveraddressed node is suspended in the middle of the transfer by saidtransferring means.